Investigating Site-Specific Parameters for Seismic Hazard Analysis in Büyükçekmece District of Istanbul: Field Study and HVSR Analysis

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This study aims to enhance our understanding of seismic hazards in Büyükçekmece by investigating site-specific parameters. We conducted a comprehensive field study involving seismic ambient vibration measurements at 56 selected locations. The horizontal-to-vertical spectral ratio (HVSR) method was employed to analyze the recorded data, and to obtain fundamental frequencies and approximate bedrock depths. These parameters offer insights into the local soil conditions and site amplification characteristics. The findings of this study reveal that the region exhibits intermediate to strong site amplification due to the contrast between alluvial deposits and Paleozoic bedrock. Peak frequencies ranged from 1.4 to 2 Hz, with amplification factors typically ranging from 1.5 to 2. Bedrock depths varied from 73 to 108 meters, and average shear wave velocities to bedrock (V Z ) showed minimal variation (576 to 608 m/s). Correlations between fundamental frequencies (f 0 ) and V S30 values demonstrate the influence of soil properties on ground motion amplification. This study contributes crucial information for seismic hazard assessment and risk reduction in Büyükçekmece. The results are invaluable for informing ground motion simulations, and and facilitating improved earthquake impact predictions. Understanding site-specific characteristics is essential for enhancing the resilience of earthquake-prone regions like Büyükçekmece district of Istanbul. Overall, this research stresses the significance of site-specific investigations in improving our understanding of seismic hazard and risk. Istanbul seismic ambient vibration site amplification HVSR fundamental frequency depth-to-bedrock Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 1. Introduction The district of Büyükçekmece in Istanbul lies within a region prone to significant seismic activity, making it susceptible to earthquakes. Over the years, the area has witnessed many seismic incidents, with the 1999 İzmit earthquake standing out as a particularly devastating event, causing widespread destruction and loss of life. Given the potentially catastrophic consequences of earthquakes in this region, it becomes imperative to gain insight into site-specific factors that can impact the severity of seismic events. These factors encompass soil conditions and site amplification characteristics, which have the capacity to influence the intensity and duration of ground motion during an earthquake. The importance of conducting seismic hazard and risk assessments cannot be overstated, as they play an important role in understanding the impacts of earthquakes on a region. In the scope of this research, our objective is to enhance our understanding of the seismic hazard present in the Büyükçekmece district by undertaking a field study involving the measurement of seismic ambient vibrations. Following the measurements, we processed these recorded data and subject them to analysis using the HVSR method. In this part, we examined fundamental frequencies and approximate depths of the underlying bedrock to observe the unique soil conditions within the area. The insights gathered from these analyses hold significant value, as they can be utilized as input for ground motion simulations, enabling us to predict the potential impact of earthquakes on the region. Our study places specific emphasis on the Murat Çeşme neighborhood within Büyükçekmece, which bears particular importance in terms of its earthquake risk profile. Situated atop soft sediment deposits, this neighborhood has experienced a substantial surge in population. Notably, its population increased by a remarkable 77% from 2010 to 2020, with an estimated population of 17,316 in 2020. The urbanized portion of the neighborhood constitutes 68% of its total area, featuring a mix of residential structures, roads, commercial establishments, and urban green spaces, as highlighted in the City Scoping Report for the Büyükçekmece District (2022). By understanding the site conditions and amplification characteristics, we can more accurately assess the seismic hazard and risk in the Büyükçekmece district and take necessary precautions to reduce potential damage and loss of life. 2. Geological characteristics of the study region The west of Istanbul is formed by two main geological settings, with the southern and western parts covered by soft sediments and the northern and northeastern sections dominated by Paleozoic bedrock. The Paleozoic basements are composed of Devonian limestone formations while the upper Miocene sediments consist of the Bakırköy formation of the upper Miocene, the Güngören formation of the middle Miocene, the Çukurçeşme formation, the Late Quaternary Kuşdili formation and alluvial deposits of Quaternary age. The alluvial deposits and other softer sediments represent the most significant geological units as they are susceptible to site amplification of the ground shaking, leading to strong site effects due to the contrast between their poor mechanical characteristics and the Paleozoic bedrock. Büyükçekmece district, characterized by relatively flat terrain and plains, ranges in elevation from 0 to 150 meters above sea level. The topography is marked by a network of valleys, with the widest and flattest oriented in a north-south direction. The slope surrounding Büyükçekmece Lake varies between 10° to 35°, while other areas of the district feature low slopes of 0–3% and 3–7%. As the majority of the urban development in the district is located at sea level, the district center exhibits a low or negligible slope. However, the slope gradually increases to over 15% in the western and northwestern portions of the district (City Scoping Report for Büyükçekmece District, 2022). Active landslides in the vicinity are primarily concentrated on the slopes overlooking the Marmara Sea and the eastern slopes of Büyükçemece Lake, while potential landslides are progressively spreading throughout the region. Fossil (residual) landslides are notably prevalent on both the western and eastern slopes of Haramidere. In these districts, there are a total of 122 potential landslide areas and 3 areas at high risk. Furthermore, there are 8 potential rockfall areas, although none of them are presently active, as reported by IMM in 2020. More details on the geological characteristics of the area can be found at City Scoping Report for Büyükçekmece District. (2022). 3. Methodology 3.1. Field Study of Seismic Ambient Vibration To understand the site response of Büyükçekmece district better, we conducted a field study of measuring seismic ambient vibration, covering approximately 6 km 2 of area (Fig. 1 ). This involved 14 visits to the site, where we recorded approximately three-hour long seismic vibrations at four selected locations each time. A total of 56 recordings were obtained from these measurements (Fig. 2 ). Our team decided to conduct ambient vibration measurements at consistent times of each day to obtain accurate results. Transient motions, which are vibrations that occur due to external factors such as passing vehicles or construction activities, can significantly impact the measured vibration levels. Such motions can vary greatly depending on the time of day, with peak levels occurring during busy hours. Therefore, by conducting our measurements during the late hours of the day, we were able to minimize the impact of transient motions and obtain more accurate and consistent results. By doing so, we gathered comprehensive and reliable data that can be used to improve our understanding of the local site response. Further details on the recordings and locations are available in Appendix A . 3.2 Processing of Recordings In the latter stage of the study, the seismic ambient vibration recordings were carefully checked and processed, and investigated using the horizontal-to-vertical spectral ratio (HVSR) method to observe site amplification at each location (Nakamura, 1989 ). The HVSR method is selected for our study due to its simplicity and effectiveness in extracting fundamental frequencies of seismic signals. Its robustness lies in the fact that it does not require prior knowledge of the subsurface structure and can be applied to various types of seismic signals, making it a widely used technique in field studies. First, all the recordings were visually checked and the truncated parts, usually appearing at the beginning and at the end of the recordings, were removed. Next, the recordings were windowed to 1-minute-long parts by utilizing a moving window shifting by 20-seconds (Fig. 3 ). This process was done by following the proposed processing method of SESAME ( 2004 ). To avoid transient motions, we also implemented an algorithm to capture and remove them from the dataset. The method for identifying transients relies on a conventional contrast between the short-term average (STA) - which represents the signal's average amplitude over a brief timeframe (1.0 second in this study) - and the long-term average (LTA) - which represents the average amplitude level of the signal over a much lengthier duration (20.0 seconds in this study). The passing value of the STA/LTA ratio is set to below 2 in our study - meaning that any window involving a ratio above this threshold is eliminated. The useable amount of the 1-minute-long windows ranged from 9.4–59.9% out of all windows, depending on the station. The station with the lowest number of usable windows has 50 windows, while the station with the highest number of usable windows has 343 windows involved in the HVSR analyses. More statistical information on the recordings and the processing can be found in Appendix B . The HVSR method was then used to determine the individual amplification curves and then, calculate the mean curves. To achieve this, simply, we calculated the geometric mean of the Fourier amplitude spectra (FAS) of the horizontal components of each 1-minute-long recordings, and divided them by the FAS of the vertical components. Through this process, at each measurement location, we could assess a high number of HVSR curves. Then, by using these individual curves, at each measurement location, we determined the mean HVSR curves and their standard deviations (A1 and B1 in Fig. 4 ) for the 0.3-4 Hz range. The HVSR analysis was also performed by considering the rotational dependency of the curves. The main reason for applying this process is to get a clearer view of the amplified frequency ranges, which is not always a possible case when only the conventional HVSR calculations are involved. In this stage, unlike in the conventional HVSR calculation, each of the horizontal components was divided by the vertical component separately, instead of getting just one horizontal-to-vertical component ratio. This calculation was applied by rotating the horizontal components by 10 degrees at each calculation. The results were plotted in two different ways – each calculated spectrum at each rotation as curves (A2 and B2 of Fig. 4 ) and as heatmap (A3 and B3 of Fig. 4 ). This helped us to have a better insight into the variations in site amplification at different orientations of the recordings and account for this in our analysis. The HVSR curves show that, in general, the mean curves tend to approach a factor of 1 at low frequencies, indicating similar spectral values between the horizontal and vertical spectra. However, many curves also go below the factor of 1 (mostly between 0.7–0.9) at low frequencies, indicating deamplification. There is no particular spatial distribution of deamplified curves, except for a grouping in the southernmost part of the region (locations 51, 54, 55, and 56). The rotational HVSR curves show that amplification can reach up to a factor of 3.8 at amplified ranges, while for the same observation, the conventional HVSR curves show an amplification factor reaching up to a factor of 3.2. Some curves also remain stable around a factor of 1 up to 4 Hz without any significant amplification. 3.3 Investigation of Fundamental Frequencies Fundamental frequency (f 0 ) also known as the "dominant frequency", refers to the lowest frequency that is most strongly represented in the ground motion response at a particular site (Lermo and Chávez-García, 1993 ; Field and Jacob, 1995 ; Bonilla et al., 1997 ; Konno and Ohmachi, 1998 ; Kawase et al., 2011 ; Ghofrani et al., 2013 ). It is a key parameter used to characterize the soil layers that make up the site's subsurface. The fundamental frequency is an important factor in determining the site's seismic response, as it affects the expected ground motion intensity and seismic noise levels. It is commonly measured using a variety of techniques, including seismic ambient vibration measurements, seismic refraction surveys, and surface wave analysis. It has been noted by various researchers that the fundamental frequency is a result of multiple reflections of the horizontal component of the shear wave (Nakamura, 2019 ; Maghami et al., 2021 ). However, it is important to note that the HVSR method may underestimate the level of site amplification (Field and Jacob, 1995 ; Bonilla et al., 1997 ), as it assumes that the vertical component has negligible amplification at the fundamental frequency, which is not always the case. Among the several studies prepared to characterize the seismic site response of Istanbul, many of them focus on estimating the fundamental frequencies of subsurface soil layers. The study of Picozzi et al. ( 2009 ) focuses on characterizing local site effects in the western part of Istanbul through passive seismic techniques such as HVSR curves and 2D micro-array techniques. In Picozzi et al. ( 2009 ), 192 single station measurements for the HVSR curves and eight 2D micro-array measurements were carried out to estimate the fundamental resonance frequency of the sedimentary cover and the local S-wave velocity profiles. Zulfikar et al. ( 2012 ) analyzed 11 earthquakes recorded in central Istanbul by the Istanbul Earthquake Rapid Response and Early Warning System (IERRWS), to identify the fundamental frequencies of station sites and investigate the consistency of site response by utilizing the HVSR method. The results showed that the IERRWS stations were located at sites with fundamental frequencies in the range of f 0 < 1.0 Hz to 3.0 Hz < f 0 < 5.0 Hz, with NEHRP D site class stations having higher fundamental frequencies than NEHRP C site class stations. The fundamental frequencies in our study were investigated over the HVSR curves, derived by making use of the seismic ambient vibration measurements and then selected over the amplified frequency bands at each of 56 measurement locations. Using the conventional method of Nakamura ( 1989 ) to calculate HVSR curves didn’t always allow us to clearly assess the fundamental frequencies, as the expected peak wasn’t always apparent when this method was used. This is likely to be caused by the issue addressed by Field and Jacob ( 1995 ) and Bonilla et al. ( 1997 ), that the vertical components also involve some amount of amplification. To give a better insight and to help overcome this issue, the rotated HVSR curves were calculated as well, that is a variation of the conventional HVSR approach. Therefore, in many of such cases, we observed clearer amplification peaks. Overall, we could assess f 0 at 42 locations out of 56, ranging between 1.4 to 2 Hz. To reinforce these estimations, we also calculated the fundamental frequencies at three nearby seismic stations using the earthquake recordings at these stations. These stations are MAEIO, BCYCO and SINB, within the Istanbul Early Warning and Rapid Response System (IEWRRS) of Department of Earthquake Engineering of Kandilli Observatory and Earthquake Research Institute. One convincing reason to extend our study to this additional analysis is that all three of these stations are not only close but also they have similar soil conditions – their V S30 values assigned from the ranging from 301 m/s, 303 m/s and 422 m/s for BCYCO, SINB and MAEIO, respectively. The magnitude of these recordings range from M W 3.7 to M W 5.7 and at each station we could make use of the S-wave windows of 20 to 44 recordings to calculate HVSRs. In all three stations we observe high amplification values at all low-to-intermediate level of frequencies, exceeding the factor of 2 – which makes it very challenging selecting the f 0 s (Fig. 5 ). However, we could only select f 0 at BCYCO, giving us a relatively clearer peak at 1.5 Hz – that is within the 1.4-2.0 Hz range, calculated for our study region. 3.4 Depth-to-bedrock and average shear wave velocity to bedrock (V Z ) calculations Following the f 0 estimations, we also calculated the depth-to-bedrock depths of this neighborhood for the locations where we could obtain f 0 values, by making use of the empirical relationships developed by Birgoren et al. (2009). The relationship is formulated as: $$H=150.99{f}_{0}^{-1.1531}$$ 1 Where H represent the depth-to-bedrock in meters. The bedrock depths range from 73 to 108 meters. Since H can be calculated through this relationship, the Kramer’s (1996) method can be applied to calculate the approximate shear wave velocity (V Z ) to the bedrock by this equation: $${V}_{Z}=4H\times {f}_{0}$$ 2 The V Z values were determined to be within a narrow range of 576 to 608 m/s, indicating minimal variability. The V S30 values at the measurement locations were obtained by interpolating values from the digital version of the V S30 grid map, which was developed by the Istanbul Metropolitan Municipality in 2007 and updated in 2009 (IMM 2007; IMM 2009). The V S30 values ranged from 263 m/s to 340 m/s. Figure 6 , Fig. 7 and Fig. 8 show geospatial distribution of f 0 , V S30 and bedrock depths, respectively, for all 42 locations where f 0 was determined. The calculated V S30 , f 0 , V Z and bedrock depths are also listed in Table 1 . As can be seen in Fig. 6and Fig. 8 , there is no specific tendency in the estimated values towards any direction in the area. Table 1 V S30 , f 0 , V Z and bedrock depths Location number V S,30 (m/s) f 0 (Hz) Depth to bedrock (m) V Z (m/s) 1 263 1.6 93 596 2 308 1.7 87 591 3 340 1.6 93 596 4 339 1.6 93 596 5 337 1.7 87 591 6 337 - - - 7 337 - - - 8 329 1.7 87 591 9 325 1.6 93 596 10 322 1.6 93 596 11 320 1.4 109 608 12 319 1.8 81 586 13 307 - - - 14 313 1.7 87 591 15 309 1.6 93 596 16 314 1.6 93 596 17 339 1.7 87 591 18 338 - - - 19 337 - - - 20 333 - - - 21 328 1.6 93 596 22 323 1.6 93 596 23 317 1.8 81 586 24 311 1.8 81 586 25 307 1.7 87 591 26 325 1.6 93 596 27 322 - - - 28 295 1.6 93 596 29 288 1.5 100 602 30 295 1.5 100 602 31 323 1.6 93 596 32 326 - - - 33 325 1.7 87 591 34 323 - - - 35 318 1.5 100 602 36 312 1.7 87 591 37 308 1.8 81 586 38 302 - - - 39 298 - - - 40 320 1.6 93 596 41 307 1.5 100 602 42 287 1.7 87 591 43 287 1.6 93 596 44 307 1.6 93 596 45 309 1.7 87 591 46 310 1.6 93 596 47 308 - - - 48 306 1.6 93 596 49 302 1.6 93 596 50 299 - - - 51 296 1.7 87 591 52 293 2 72 576 53 297 1.7 87 591 54 298 1.7 87 591 55 300 1.6 93 596 56 298 - - - 4. Analyses and discussion Following the preliminary observations of the HVSR curves and the selection of f 0 values, several analyses were carried out to gain a better understanding of the estimated values. To obtain a meaningful insight into the distribution of the amplification factors, we first isolated the amplification factors at specific frequencies. This allowed us to examine how the amplification distribution appeared for each frequency and see if certain spatial groupings in amplification were evident at certain frequencies. We focused on four frequencies, namely 1.4, 1.6, 1.8 and 2.0 Hz, since these were the frequencies at which we could choose the f 0 values. Figure 9 illustrates the distribution of the maximum observed amplification factors among the rotated mean HVSR curves, at these selected frequencies. The figure reveals no clear pattern in the spatial distribution of these values. However, it does enable us to identify the most significant changes within the 1.4-2.0 Hz range. The stations situated along the western and southern border of the study area tend to exhibit the least changes in amplification, indicating minor changes in the amplification. On the other hand, a number of stations located in the middle and northwest of the region show more changes in the amplification. Gaining insight into the geographical distribution of amplification factors can aid in identifying regions that may be at a higher risk for potential hazards. Nevertheless, it is evident that this is not applicable to our study region. When observing the rotated mean curves, we can see that the amplification factors can reach up to 2.5 at f 0 s. However, this comes with a margin of error, which is typically expressed by the sigma parameter. As the amplification levels increase, the individual spectra of the recordings at an observation point tend to have more variations. At peak frequencies, the directional dependency of the mean HVSR curves becomes even higher when the amplification factors are higher, making this approach even more significant for such cases. In our case, having an amplification factor of 2.5 may indicate a high probability of having a peak value above the level of 3. This also highlights the vulnerability of this region in the event of a large earthquake. Figure 10 in our study demonstrates the clear correlation between amplification factors and sigma values, making it a significant concern for earthquake hazard analysis. These amplification factors are derived as the maximums of the observed rotated mean HVSR curves. The f 0 parameter, that is investigated in this study, is influenced by the soil properties. Softer soils tend to have lower f 0 values, meaning that they amplify lower frequency ground motion – which is the case in our study area. Therefore, by correlating f 0 and V S30 , we can better understand how the soil properties affect the amplification of ground motion during an earthquake. This information is also crucial for our ground motion modeling. The correlation between f 0 and V S30 has been investigated in many past studies (e.g., Ghofrani and Atkinson 2014 ; Hassani and Atkinson 2016 ). These studies has shown the relation between f 0 and V S30 , yielding different models at different regions. The relationship between V S30 and the parameters of the H/V curve (A peak and f peak ) was established by Ghofrani and Atkinson ( 2014 ) using data from the Japanese KNET and KiK-NET stations. The relationship was found to be applicable to earthquake records from various parts of the world, including Italy, Japan, China, Taiwan, and Northern and Southern California, as observed in the NGA-West 2 database. By using data from CENA, Hassani and Atkinson ( 2016 ) determined the peak frequencies of the HVSR curves, which were then employed as predictive parameters to analyze site effects. Figure 11 presents the distribution of the selected f 0 values against V S30 and compares them with the models proposed in Ghofrani and Atkinson ( 2014 ) and Hassani and Atkinson ( 2016 ). The distribution of our data falls between the two models; however, developing a model based on our data points is challenging due to the relatively low number of observations and the limited soil variability in our study area. Nevertheless, comparing the distribution of our estimates with similar models adds further validation to our results. Furthermore, we compared our f 0 estimations with the ones obtained from the AFAD stations situated across the wider Marmara region. Due to the expansive coverage area of these AFAD stations, the variability in their estimations was significantly higher. In fact, their estimations were scattered both around our data points and the pre-existing models mentioned earlier. Consequently, correlating the AFAD estimations with V S30 posed a considerable challenge. In order to provide a comprehensive overview of our findings, we have included a graphical representation of our data points, existing models, the AFAD estimations, and the f 0 estimated for the BCYCO station in Fig. 12 . 5. Conclusion The purpose of this study was to identify and evaluate the site-specific parameters of the Büyükçekmece district of Istanbul, which is located in a region with a high level of seismicity and is thus susceptible to earthquakes. The unique characteristics of the study region, including soil conditions and site amplification characteristics, can influence the intensity and duration of ground motion during an earthquake, making it crucial to understand these factors for predicting the impacts of earthquakes on the region and implementing necessary precautions to reduce damage and loss of life. To investigate the site-specific parameters of the Büyükçekmece district, we conducted a field study of measuring seismic ambient vibration and processed the recordings using well-known approaches in the literature. The HVSR method was used to investigate site amplification, and fundamental frequencies and bedrock depths were also examined to gain insight into the soil conditions at the site. The results of these analyses provide valuable information for understanding the site-specific behaviour of the Büyükçekmece district, and can be utilized in ground motion simulations to predict the potential impact of earthquakes on the region. Our findings demonstrate that the Büyükçekmece district exhibits intermediate to strong site amplification due to the contrast between the poor mechanical characteristics of the alluvial deposits and other softer sediments and the Paleozoic bedrock. The HVSR curves revealed peak frequencies ranging from 1.4 to 2 Hz. In most cases, the amplification factors at these frequencies ranged from 1.5 to 2, with no specific geographical tendency within the study area. The estimated bedrock depths varied from 73 to 108 meters. The following average shearwave estimations also yielded values of 576 to 608 m/s, demonstrating minimal variation. Our study contributes to a deeper understanding of the seismic hazard in the Büyükçekmece district and provides useful information for future risk assessments. By understanding the site conditions and amplification characteristics, we can more accurately assess the seismic hazard and risk in the study region and take necessary precautions to reduce potential damage and loss of life. The results of our study will be used as input for ground motion simulations to predict the potential impact of earthquakes on the region, which can inform hazard mitigation strategies and help to reduce the potential impact of future earthquakes. Overall, our study highlights the importance of site-specific investigations for improving our understanding of seismic hazard and risk in earthquake-prone regions. Declarations Acknowledgments We would like to express our sincere gratitude to the Department of Earthquake Engineering at Boğaziçi University for their important technical support throughout this project. We particularly wish to thank the technical team for their assistance in placing and recording the ambient vibrations. Their expertise and dedication were essential to the success of this study. We are grateful for the opportunity to work with such a supportive group of professionals. Funding This work has been supported by UKRI-GCRF in the framework of project “Tomorrow’s Cities”. Conflict of interest The authors declare that they have no conflict of interest. Availability of data and material The study is based on the data from the Istanbul Earthquake Rapid Response and Early Warning System operated by the Department of Earthquake Engineering of Boğaziçi University’s Kandilli Observatory and Earthquake Research Institute and from AFAD. 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Supplementary Files Appendix.docx Cite Share Download PDF Status: Published Journal Publication published 01 Apr, 2025 Read the published version in Bulletin of Earthquake Engineering → Version 1 posted Editorial decision: Major Revisions Needed 09 Oct, 2024 Reviewers agreed at journal 21 Dec, 2023 Reviewers invited by journal 26 Oct, 2023 Editor assigned by journal 26 Oct, 2023 First submitted to journal 25 Oct, 2023 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3497875","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":243273144,"identity":"a4dff6e8-45fd-43f4-98c5-4846a0421076","order_by":0,"name":"Hakan Süleyman","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABC0lEQVRIiWNgGAWjYBACAwY2CIMPQtkkQGg2IrRAqTSEFh4itRwmrMWc/Vji5wKGusQ29h7TDT93nM/jl8g9wPCh7DCDvfQBrFose9IOS89gOJzYxnPG7GbvmdvFkjPyEhhnnDvMwMOXgN1hB9IbpHkYDiS2SeSY3eBtu5244UaOATNvG1ALDpcZnH/e/JsH5DD5N2Y3/7adg2j5i0/LjbRjQFuYgbbwmN3mbTsA0cKIV8uzNGseg8PGbTxpZbdl25KLJXveGBzsOZfOw3MGl8PSjG/zVNTJ9rMf3nbzbZtdHj97juGDH2XWcuw92LVANYIIDgM4/wAD7mhBBuwPiFA0CkbBKBgFIxEAALO4W1X+Hj0fAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-5536-4747","institution":"Boğaziçi University, Kandilli Observatory and Earthquake Research Institute","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Hakan","middleName":"","lastName":"Süleyman","suffix":""},{"id":243273145,"identity":"2a7b85ca-69f5-400b-ac51-13aae9b3dda9","order_by":1,"name":"Eser Çaktı","email":"","orcid":"","institution":"Boğaziçi University, Kandilli Observatory and Earthquake Research Institute","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Eser","middleName":"","lastName":"Çaktı","suffix":""},{"id":243273146,"identity":"db026dcd-dd47-4d55-ac9c-980f8919a56d","order_by":2,"name":"Emrullah Dar","email":"","orcid":"","institution":"Boğaziçi University, Kandilli Observatory and Earthquake Research Institute","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Emrullah","middleName":"","lastName":"Dar","suffix":""}],"badges":[],"createdAt":"2023-10-27 07:09:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3497875/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3497875/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10518-025-02129-6","type":"published","date":"2025-04-01T15:57:20+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":45578657,"identity":"8c10c881-c8f4-46c9-b2fd-67a873aebe82","added_by":"auto","created_at":"2023-10-31 18:04:18","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1307566,"visible":true,"origin":"","legend":"\u003cp\u003eThe location of the study area; adapted from City Scoping Report for Büyükçekmece District (2022)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/d92f1b747e7ce1f2289f4100.png"},{"id":45579070,"identity":"04343694-fa68-4b84-b389-ad1d95b564a3","added_by":"auto","created_at":"2023-10-31 18:12:19","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":51625,"visible":true,"origin":"","legend":"\u003cp\u003eThe distribution of the ambient vibration measurement locations\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/6127253cb31d08f46b2f8d0b.jpg"},{"id":45577521,"identity":"644fd53b-741b-4a9e-9302-cfdb19e0ba07","added_by":"auto","created_at":"2023-10-31 17:56:18","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":650693,"visible":true,"origin":"","legend":"\u003cp\u003eVisualization of the windowing process\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/22222d45098f918b767b59ac.png"},{"id":45577526,"identity":"57f233c2-c9cb-4fa5-ad49-274fea01f777","added_by":"auto","created_at":"2023-10-31 17:56:19","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":667232,"visible":true,"origin":"","legend":"\u003cp\u003eHVSR analyses at two selected locations; A1 and B1 - the conventional HVSR estimation (black lines show the individual estimations, the solid red line show the mean curve and blue dashed line show ±1 standard deviation); A2 and B2 - the rotational dependence of the HVSR curves (the thick lines represent NS/V and EW/V spectral ratios, while the thin lines represent NS/V rotated by 10 degree increments); A3 and B3 – the heatmaps of the rotational HVSR curves (the color scale show the change in amplification)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/43fda05ce8c4cc2dfcaf709d.png"},{"id":45577524,"identity":"374675fd-7339-43b9-b085-07e78311ce55","added_by":"auto","created_at":"2023-10-31 17:56:19","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":311416,"visible":true,"origin":"","legend":"\u003cp\u003eHVSR analyses at three stations nearby the study region – black lines show the individual estimations, the solid red line show the mean curve and blue dashed line show ±1 standard deviation\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/adee643d672117b5d6119123.png"},{"id":45577523,"identity":"5ace8bad-bad3-46de-a465-ba79fd32245b","added_by":"auto","created_at":"2023-10-31 17:56:18","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":329924,"visible":true,"origin":"","legend":"\u003cp\u003eFundamental frequency (f\u003csub\u003e0\u003c/sub\u003e) distribution\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/86f5da335fb68bfa65a1ea51.png"},{"id":45578662,"identity":"dee03a8a-5cab-4de4-a05f-9de76c0e97a6","added_by":"auto","created_at":"2023-10-31 18:04:19","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":345451,"visible":true,"origin":"","legend":"\u003cp\u003eThe distribution of the V\u003csub\u003eS30\u003c/sub\u003e values assigned from the V\u003csub\u003eS30\u003c/sub\u003e grid map of IMM (2007) and IMM (2009) prepared for Istanbul\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/1911ad72801ee501324971cb.png"},{"id":45577530,"identity":"173ec02a-df74-4b37-91ca-78e04681858b","added_by":"auto","created_at":"2023-10-31 17:56:19","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":340091,"visible":true,"origin":"","legend":"\u003cp\u003eDepth-to-bedrock distribution\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/2e0c0420a23f8cf6951b17d5.png"},{"id":45578658,"identity":"b0d869f3-3439-4cc1-9daa-e3911d1b6186","added_by":"auto","created_at":"2023-10-31 18:04:19","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":753588,"visible":true,"origin":"","legend":"\u003cp\u003eSpatial distribution of amplification factors at 1.4, 1.6, 1.8 and 2.0 Hz, derived as the maximum of the rotated mean HVSR curves\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/97ea81e79c345c3cf49068fd.png"},{"id":45577531,"identity":"99c67b82-b9f6-4170-a8f2-cd59d1e776b9","added_by":"auto","created_at":"2023-10-31 17:56:19","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":151998,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation between sigma and amplification factors at 1.4, 1.6, 1.8 and 2.0 Hz, derived as the maximum of the rotated mean HVSR curves\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/1f3f92fd0e80dd184276eaf7.png"},{"id":45578661,"identity":"4af09632-6ddf-4e76-9758-30a0697ea5fb","added_by":"auto","created_at":"2023-10-31 18:04:19","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":230176,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of selected f\u003csub\u003e0\u003c/sub\u003e values with existing models; The blue circles represent the selected f\u003csub\u003e0\u003c/sub\u003e values in our study, while the dashed lines represent the models developed by Ghofrani and Atkinson (2014) and Hassani and Atkinson (2016).\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/e1e7478385838d7b9fff64bb.png"},{"id":45578659,"identity":"bb6e6c18-d88c-4e35-82ab-610142c961bb","added_by":"auto","created_at":"2023-10-31 18:04:19","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":362558,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of selected f\u003csub\u003e0\u003c/sub\u003e values with AFAD f\u003csub\u003e0\u003c/sub\u003e estimations and existing models; The blue circles represent the selected f\u003csub\u003e0\u003c/sub\u003e values in our study, the red squares represent AFAD f\u003csub\u003e0\u003c/sub\u003e estimations, the red triangle represents the BCYCO station f\u003csub\u003e0\u003c/sub\u003e estimation and\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/5ba60f23afed009d8c77d998.png"},{"id":80082029,"identity":"a11cfc91-e4cd-4989-be90-23a8764eb42a","added_by":"auto","created_at":"2025-04-07 16:05:56","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5980896,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/13245e8c-4c55-4de8-9eae-71d0668ddb99.pdf"},{"id":45577520,"identity":"59d99211-9132-47d5-bb36-5d02298c15d3","added_by":"auto","created_at":"2023-10-31 17:56:18","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":61085,"visible":true,"origin":"","legend":"","description":"","filename":"Appendix.docx","url":"https://assets-eu.researchsquare.com/files/rs-3497875/v1/f4c59e879e1a6d915f314528.docx"}],"financialInterests":"","formattedTitle":"Investigating Site-Specific Parameters for Seismic Hazard Analysis in Büyükçekmece District of Istanbul: Field Study and HVSR Analysis","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe district of B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece in Istanbul lies within a region prone to significant seismic activity, making it susceptible to earthquakes. Over the years, the area has witnessed many seismic incidents, with the 1999 İzmit earthquake standing out as a particularly devastating event, causing widespread destruction and loss of life. Given the potentially catastrophic consequences of earthquakes in this region, it becomes imperative to gain insight into site-specific factors that can impact the severity of seismic events. These factors encompass soil conditions and site amplification characteristics, which have the capacity to influence the intensity and duration of ground motion during an earthquake.\u003c/p\u003e \u003cp\u003eThe importance of conducting seismic hazard and risk assessments cannot be overstated, as they play an important role in understanding the impacts of earthquakes on a region. In the scope of this research, our objective is to enhance our understanding of the seismic hazard present in the B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district by undertaking a field study involving the measurement of seismic ambient vibrations. Following the measurements, we processed these recorded data and subject them to analysis using the HVSR method. In this part, we examined fundamental frequencies and approximate depths of the underlying bedrock to observe the unique soil conditions within the area. The insights gathered from these analyses hold significant value, as they can be utilized as input for ground motion simulations, enabling us to predict the potential impact of earthquakes on the region.\u003c/p\u003e \u003cp\u003eOur study places specific emphasis on the Murat \u0026Ccedil;eşme neighborhood within B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece, which bears particular importance in terms of its earthquake risk profile. Situated atop soft sediment deposits, this neighborhood has experienced a substantial surge in population. Notably, its population increased by a remarkable 77% from 2010 to 2020, with an estimated population of 17,316 in 2020. The urbanized portion of the neighborhood constitutes 68% of its total area, featuring a mix of residential structures, roads, commercial establishments, and urban green spaces, as highlighted in the City Scoping Report for the B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece District (2022).\u003c/p\u003e \u003cp\u003eBy understanding the site conditions and amplification characteristics, we can more accurately assess the seismic hazard and risk in the B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district and take necessary precautions to reduce potential damage and loss of life.\u003c/p\u003e"},{"header":"2. Geological characteristics of the study region","content":"\u003cp\u003eThe west of Istanbul is formed by two main geological settings, with the southern and western parts covered by soft sediments and the northern and northeastern sections dominated by Paleozoic bedrock. The Paleozoic basements are composed of Devonian limestone formations while the upper Miocene sediments consist of the Bakırk\u0026ouml;y formation of the upper Miocene, the G\u0026uuml;ng\u0026ouml;ren formation of the middle Miocene, the \u0026Ccedil;ukur\u0026ccedil;eşme formation, the Late Quaternary Kuşdili formation and alluvial deposits of Quaternary age. The alluvial deposits and other softer sediments represent the most significant geological units as they are susceptible to site amplification of the ground shaking, leading to strong site effects due to the contrast between their poor mechanical characteristics and the Paleozoic bedrock.\u003c/p\u003e \u003cp\u003eB\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district, characterized by relatively flat terrain and plains, ranges in elevation from 0 to 150 meters above sea level. The topography is marked by a network of valleys, with the widest and flattest oriented in a north-south direction. The slope surrounding B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece Lake varies between 10\u0026deg; to 35\u0026deg;, while other areas of the district feature low slopes of 0\u0026ndash;3% and 3\u0026ndash;7%. As the majority of the urban development in the district is located at sea level, the district center exhibits a low or negligible slope. However, the slope gradually increases to over 15% in the western and northwestern portions of the district (City Scoping Report for B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece District, 2022).\u003c/p\u003e \u003cp\u003eActive landslides in the vicinity are primarily concentrated on the slopes overlooking the Marmara Sea and the eastern slopes of B\u0026uuml;y\u0026uuml;k\u0026ccedil;emece Lake, while potential landslides are progressively spreading throughout the region. Fossil (residual) landslides are notably prevalent on both the western and eastern slopes of Haramidere. In these districts, there are a total of 122 potential landslide areas and 3 areas at high risk. Furthermore, there are 8 potential rockfall areas, although none of them are presently active, as reported by IMM in 2020.\u003c/p\u003e \u003cp\u003eMore details on the geological characteristics of the area can be found at City Scoping Report for B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece District. (2022).\u003c/p\u003e"},{"header":"3. Methodology","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n\u003ch2\u003e3.1. Field Study of Seismic Ambient Vibration\u003c/h2\u003e\n\u003cp\u003eTo understand the site response of B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district better, we conducted a field study of measuring seismic ambient vibration, covering approximately 6 km\u003csup\u003e2\u003c/sup\u003e of area (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). This involved 14 visits to the site, where we recorded approximately three-hour long seismic vibrations at four selected locations each time. A total of 56 recordings were obtained from these measurements (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eOur team decided to conduct ambient vibration measurements at consistent times of each day to obtain accurate results. Transient motions, which are vibrations that occur due to external factors such as passing vehicles or construction activities, can significantly impact the measured vibration levels. Such motions can vary greatly depending on the time of day, with peak levels occurring during busy hours. Therefore, by conducting our measurements during the late hours of the day, we were able to minimize the impact of transient motions and obtain more accurate and consistent results. By doing so, we gathered comprehensive and reliable data that can be used to improve our understanding of the local site response. Further details on the recordings and locations are available in \u003cspan class=\"InternalRef\"\u003eAppendix A\u003c/span\u003e.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n\u003ch2\u003e3.2 Processing of Recordings\u003c/h2\u003e\n\u003cp\u003eIn the latter stage of the study, the seismic ambient vibration recordings were carefully checked and processed, and investigated using the horizontal-to-vertical spectral ratio (HVSR) method to observe site amplification at each location (Nakamura, \u003cspan class=\"CitationRef\"\u003e1989\u003c/span\u003e). The HVSR method is selected for our study due to its simplicity and effectiveness in extracting fundamental frequencies of seismic signals. Its robustness lies in the fact that it does not require prior knowledge of the subsurface structure and can be applied to various types of seismic signals, making it a widely used technique in field studies.\u003c/p\u003e\n\u003cp\u003eFirst, all the recordings were visually checked and the truncated parts, usually appearing at the beginning and at the end of the recordings, were removed. Next, the recordings were windowed to 1-minute-long parts by utilizing a moving window shifting by 20-seconds (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). This process was done by following the proposed processing method of SESAME (\u003cspan class=\"CitationRef\"\u003e2004\u003c/span\u003e). To avoid transient motions, we also implemented an algorithm to capture and remove them from the dataset. The method for identifying transients relies on a conventional contrast between the short-term average (STA) - which represents the signal's average amplitude over a brief timeframe (1.0 second in this study) - and the long-term average (LTA) - which represents the average amplitude level of the signal over a much lengthier duration (20.0 seconds in this study). The passing value of the STA/LTA ratio is set to below 2 in our study - meaning that any window involving a ratio above this threshold is eliminated.\u003c/p\u003e\n\u003cp\u003eThe useable amount of the 1-minute-long windows ranged from 9.4\u0026ndash;59.9% out of all windows, depending on the station. The station with the lowest number of usable windows has 50 windows, while the station with the highest number of usable windows has 343 windows involved in the HVSR analyses. More statistical information on the recordings and the processing can be found in \u003cspan class=\"InternalRef\"\u003eAppendix B\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003eThe HVSR method was then used to determine the individual amplification curves and then, calculate the mean curves. To achieve this, simply, we calculated the geometric mean of the Fourier amplitude spectra (FAS) of the horizontal components of each 1-minute-long recordings, and divided them by the FAS of the vertical components. Through this process, at each measurement location, we could assess a high number of HVSR curves. Then, by using these individual curves, at each measurement location, we determined the mean HVSR curves and their standard deviations (A1 and B1 in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e) for the 0.3-4 Hz range.\u003c/p\u003e\n\u003cp\u003eThe HVSR analysis was also performed by considering the rotational dependency of the curves. The main reason for applying this process is to get a clearer view of the amplified frequency ranges, which is not always a possible case when only the conventional HVSR calculations are involved. In this stage, unlike in the conventional HVSR calculation, each of the horizontal components was divided by the vertical component separately, instead of getting just one horizontal-to-vertical component ratio. This calculation was applied by rotating the horizontal components by 10 degrees at each calculation. The results were plotted in two different ways \u0026ndash; each calculated spectrum at each rotation as curves (A2 and B2 of Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e) and as heatmap (A3 and B3 of Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). This helped us to have a better insight into the variations in site amplification at different orientations of the recordings and account for this in our analysis.\u003c/p\u003e\n\u003cp\u003eThe HVSR curves show that, in general, the mean curves tend to approach a factor of 1 at low frequencies, indicating similar spectral values between the horizontal and vertical spectra. However, many curves also go below the factor of 1 (mostly between 0.7\u0026ndash;0.9) at low frequencies, indicating deamplification. There is no particular spatial distribution of deamplified curves, except for a grouping in the southernmost part of the region (locations 51, 54, 55, and 56). The rotational HVSR curves show that amplification can reach up to a factor of 3.8 at amplified ranges, while for the same observation, the conventional HVSR curves show an amplification factor reaching up to a factor of 3.2. Some curves also remain stable around a factor of 1 up to 4 Hz without any significant amplification.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003ch2\u003e3.3 Investigation of Fundamental Frequencies\u003c/h2\u003e\n\u003cp\u003eFundamental frequency (f\u003csub\u003e0\u003c/sub\u003e) also known as the \"dominant frequency\", refers to the lowest frequency that is most strongly represented in the ground motion response at a particular site (Lermo and Ch\u0026aacute;vez-Garc\u0026iacute;a, \u003cspan class=\"CitationRef\"\u003e1993\u003c/span\u003e; Field and Jacob, \u003cspan class=\"CitationRef\"\u003e1995\u003c/span\u003e; Bonilla et al., \u003cspan class=\"CitationRef\"\u003e1997\u003c/span\u003e; Konno and Ohmachi, \u003cspan class=\"CitationRef\"\u003e1998\u003c/span\u003e; Kawase et al., \u003cspan class=\"CitationRef\"\u003e2011\u003c/span\u003e; Ghofrani et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e). It is a key parameter used to characterize the soil layers that make up the site's subsurface. The fundamental frequency is an important factor in determining the site's seismic response, as it affects the expected ground motion intensity and seismic noise levels. It is commonly measured using a variety of techniques, including seismic ambient vibration measurements, seismic refraction surveys, and surface wave analysis. It has been noted by various researchers that the fundamental frequency is a result of multiple reflections of the horizontal component of the shear wave (Nakamura, \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e; Maghami et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e). However, it is important to note that the HVSR method may underestimate the level of site amplification (Field and Jacob, \u003cspan class=\"CitationRef\"\u003e1995\u003c/span\u003e; Bonilla et al., \u003cspan class=\"CitationRef\"\u003e1997\u003c/span\u003e), as it assumes that the vertical component has negligible amplification at the fundamental frequency, which is not always the case.\u003c/p\u003e\n\u003cp\u003eAmong the several studies prepared to characterize the seismic site response of Istanbul, many of them focus on estimating the fundamental frequencies of subsurface soil layers. The study of Picozzi et al. (\u003cspan class=\"CitationRef\"\u003e2009\u003c/span\u003e) focuses on characterizing local site effects in the western part of Istanbul through passive seismic techniques such as HVSR curves and 2D micro-array techniques. In Picozzi et al. (\u003cspan class=\"CitationRef\"\u003e2009\u003c/span\u003e), 192 single station measurements for the HVSR curves and eight 2D micro-array measurements were carried out to estimate the fundamental resonance frequency of the sedimentary cover and the local S-wave velocity profiles. Zulfikar et al. (\u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e) analyzed 11 earthquakes recorded in central Istanbul by the Istanbul Earthquake Rapid Response and Early Warning System (IERRWS), to identify the fundamental frequencies of station sites and investigate the consistency of site response by utilizing the HVSR method. The results showed that the IERRWS stations were located at sites with fundamental frequencies in the range of f\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;\u0026lt;\u0026thinsp;1.0 Hz to 3.0 Hz\u0026thinsp;\u0026lt;\u0026thinsp;f\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;\u0026lt;\u0026thinsp;5.0 Hz, with NEHRP D site class stations having higher fundamental frequencies than NEHRP C site class stations.\u003c/p\u003e\n\u003cp\u003eThe fundamental frequencies in our study were investigated over the HVSR curves, derived by making use of the seismic ambient vibration measurements and then selected over the amplified frequency bands at each of 56 measurement locations. Using the conventional method of Nakamura (\u003cspan class=\"CitationRef\"\u003e1989\u003c/span\u003e) to calculate HVSR curves didn\u0026rsquo;t always allow us to clearly assess the fundamental frequencies, as the expected peak wasn\u0026rsquo;t always apparent when this method was used. This is likely to be caused by the issue addressed by Field and Jacob (\u003cspan class=\"CitationRef\"\u003e1995\u003c/span\u003e) and Bonilla et al. (\u003cspan class=\"CitationRef\"\u003e1997\u003c/span\u003e), that the vertical components also involve some amount of amplification. To give a better insight and to help overcome this issue, the rotated HVSR curves were calculated as well, that is a variation of the conventional HVSR approach. Therefore, in many of such cases, we observed clearer amplification peaks. Overall, we could assess f\u003csub\u003e0\u003c/sub\u003e at 42 locations out of 56, ranging between 1.4 to 2 Hz.\u003c/p\u003e\n\u003cp\u003eTo reinforce these estimations, we also calculated the fundamental frequencies at three nearby seismic stations using the earthquake recordings at these stations. These stations are MAEIO, BCYCO and SINB, within the Istanbul Early Warning and Rapid Response System (IEWRRS) of Department of Earthquake Engineering of Kandilli Observatory and Earthquake Research Institute. One convincing reason to extend our study to this additional analysis is that all three of these stations are not only close but also they have similar soil conditions \u0026ndash; their V\u003csub\u003eS30\u003c/sub\u003e values assigned from the ranging from 301 m/s, 303 m/s and 422 m/s for BCYCO, SINB and MAEIO, respectively. The magnitude of these recordings range from M\u003csub\u003eW\u003c/sub\u003e3.7 to M\u003csub\u003eW\u003c/sub\u003e5.7 and at each station we could make use of the S-wave windows of 20 to 44 recordings to calculate HVSRs. In all three stations we observe high amplification values at all low-to-intermediate level of frequencies, exceeding the factor of 2 \u0026ndash; which makes it very challenging selecting the f\u003csub\u003e0\u003c/sub\u003es (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e). However, we could only select f\u003csub\u003e0\u003c/sub\u003e at BCYCO, giving us a relatively clearer peak at 1.5 Hz \u0026ndash; that is within the 1.4-2.0 Hz range, calculated for our study region.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n\u003ch2\u003e3.4 Depth-to-bedrock and average shear wave velocity to bedrock (V\u003csub\u003eZ\u003c/sub\u003e) calculations\u003c/h2\u003e\n\u003cp\u003eFollowing the f\u003csub\u003e0\u003c/sub\u003e estimations, we also calculated the depth-to-bedrock depths of this neighborhood for the locations where we could obtain f\u003csub\u003e0\u003c/sub\u003e values, by making use of the empirical relationships developed by Birgoren et al. (2009). The relationship is formulated as:\u003c/p\u003e\n\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equ1\" class=\"mathdisplay\"\u003e$$H=150.99{f}_{0}^{-1.1531}$$\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003eWhere H represent the depth-to-bedrock in meters. The bedrock depths range from 73 to 108 meters. Since H can be calculated through this relationship, the Kramer\u0026rsquo;s (1996) method can be applied to calculate the approximate shear wave velocity (V\u003csub\u003eZ\u003c/sub\u003e) to the bedrock by this equation:\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equ2\" class=\"mathdisplay\"\u003e$${V}_{Z}=4H\\times {f}_{0}$$\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eThe V\u003csub\u003eZ\u003c/sub\u003e values were determined to be within a narrow range of 576 to 608 m/s, indicating minimal variability. The V\u003csub\u003eS30\u003c/sub\u003e values at the measurement locations were obtained by interpolating values from the digital version of the V\u003csub\u003eS30\u003c/sub\u003e grid map, which was developed by the Istanbul Metropolitan Municipality in 2007 and updated in 2009 (IMM 2007; IMM 2009). The V\u003csub\u003eS30\u003c/sub\u003e values ranged from 263 m/s to 340 m/s.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e show geospatial distribution of f\u003csub\u003e0\u003c/sub\u003e, V\u003csub\u003eS30\u003c/sub\u003e and bedrock depths, respectively, for all 42 locations where f\u003csub\u003e0\u003c/sub\u003e was determined. The calculated V\u003csub\u003eS30\u003c/sub\u003e, f\u003csub\u003e0\u003c/sub\u003e, V\u003csub\u003eZ\u003c/sub\u003e and bedrock depths are also listed in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. As can be seen in Fig.\u0026nbsp;6and Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e, there is no specific tendency in the estimated values towards any direction in the area.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eV\u003csub\u003eS30\u003c/sub\u003e, f\u003csub\u003e0\u003c/sub\u003e, V\u003csub\u003eZ\u003c/sub\u003e and bedrock depths\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eLocation number\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eS,30\u003c/em\u003e\u003c/sub\u003e \u003cem\u003e(m/s)\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e \u003cem\u003e(Hz)\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eDepth to bedrock (m)\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e \u003cem\u003e(m/s)\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e263\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e2\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e308\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e3\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e340\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e4\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e339\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e5\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e337\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e337\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e337\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e8\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e329\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e9\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e325\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e10\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e322\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e11\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e320\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.4\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e109\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e608\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e12\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e319\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.8\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e81\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e586\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e13\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e307\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e14\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e313\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e15\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e309\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e16\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e314\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e17\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e339\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e18\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e338\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e19\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e337\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e20\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e333\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e21\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e328\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e22\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e323\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e23\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e317\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.8\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e81\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e586\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e24\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e311\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.8\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e81\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e586\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e25\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e307\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e26\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e325\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e27\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e322\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e28\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e295\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e29\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e288\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.5\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e100\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e602\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e30\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e295\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.5\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e100\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e602\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e31\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e323\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e32\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e326\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e33\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e325\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e34\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e323\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e35\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e318\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.5\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e100\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e602\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e36\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e312\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e37\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e308\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.8\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e81\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e586\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e38\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e302\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e39\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e298\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e40\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e320\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e41\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e307\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.5\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e100\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e602\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e42\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e287\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e43\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e287\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e44\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e307\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e45\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e309\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e46\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e310\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e47\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e308\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e48\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e306\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e49\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e302\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e50\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e299\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e51\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e296\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e52\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e293\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e2\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e72\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e576\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e53\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e297\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e54\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e298\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.7\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e87\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e591\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e55\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e300\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e1.6\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e93\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e596\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e56\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e\u003cem\u003e298\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003e-\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e"},{"header":"4. Analyses and discussion","content":"\u003cp\u003eFollowing the preliminary observations of the HVSR curves and the selection of f\u003csub\u003e0\u003c/sub\u003e values, several analyses were carried out to gain a better understanding of the estimated values. To obtain a meaningful insight into the distribution of the amplification factors, we first isolated the amplification factors at specific frequencies. This allowed us to examine how the amplification distribution appeared for each frequency and see if certain spatial groupings in amplification were evident at certain frequencies. We focused on four frequencies, namely 1.4, 1.6, 1.8 and 2.0 Hz, since these were the frequencies at which we could choose the f\u003csub\u003e0\u003c/sub\u003e values. Figure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e illustrates the distribution of the maximum observed amplification factors among the rotated mean HVSR curves, at these selected frequencies. The figure reveals no clear pattern in the spatial distribution of these values. However, it does enable us to identify the most significant changes within the 1.4-2.0 Hz range. The stations situated along the western and southern border of the study area tend to exhibit the least changes in amplification, indicating minor changes in the amplification. On the other hand, a number of stations located in the middle and northwest of the region show more changes in the amplification. Gaining insight into the geographical distribution of amplification factors can aid in identifying regions that may be at a higher risk for potential hazards. Nevertheless, it is evident that this is not applicable to our study region.\u003c/p\u003e \u003cp\u003eWhen observing the rotated mean curves, we can see that the amplification factors can reach up to 2.5 at f\u003csub\u003e0\u003c/sub\u003es. However, this comes with a margin of error, which is typically expressed by the sigma parameter. As the amplification levels increase, the individual spectra of the recordings at an observation point tend to have more variations. At peak frequencies, the directional dependency of the mean HVSR curves becomes even higher when the amplification factors are higher, making this approach even more significant for such cases. In our case, having an amplification factor of 2.5 may indicate a high probability of having a peak value above the level of 3. This also highlights the vulnerability of this region in the event of a large earthquake. Figure\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e in our study demonstrates the clear correlation between amplification factors and sigma values, making it a significant concern for earthquake hazard analysis. These amplification factors are derived as the maximums of the observed rotated mean HVSR curves.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe f\u003csub\u003e0\u003c/sub\u003e parameter, that is investigated in this study, is influenced by the soil properties. Softer soils tend to have lower f\u003csub\u003e0\u003c/sub\u003e values, meaning that they amplify lower frequency ground motion \u0026ndash; which is the case in our study area. Therefore, by correlating f\u003csub\u003e0\u003c/sub\u003e and V\u003csub\u003eS30\u003c/sub\u003e, we can better understand how the soil properties affect the amplification of ground motion during an earthquake. This information is also crucial for our ground motion modeling.\u003c/p\u003e \u003cp\u003eThe correlation between f\u003csub\u003e0\u003c/sub\u003e and V\u003csub\u003eS30\u003c/sub\u003e has been investigated in many past studies (e.g., Ghofrani and Atkinson \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Hassani and Atkinson \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). These studies has shown the relation between f\u003csub\u003e0\u003c/sub\u003e and V\u003csub\u003eS30\u003c/sub\u003e, yielding different models at different regions. The relationship between V\u003csub\u003eS30\u003c/sub\u003e and the parameters of the H/V curve (A\u003csub\u003epeak\u003c/sub\u003e and f\u003csub\u003epeak\u003c/sub\u003e) was established by Ghofrani and Atkinson (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) using data from the Japanese KNET and KiK-NET stations. The relationship was found to be applicable to earthquake records from various parts of the world, including Italy, Japan, China, Taiwan, and Northern and Southern California, as observed in the NGA-West 2 database. By using data from CENA, Hassani and Atkinson (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) determined the peak frequencies of the HVSR curves, which were then employed as predictive parameters to analyze site effects.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e presents the distribution of the selected f\u003csub\u003e0\u003c/sub\u003e values against V\u003csub\u003eS30\u003c/sub\u003e and compares them with the models proposed in Ghofrani and Atkinson (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) and Hassani and Atkinson (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The distribution of our data falls between the two models; however, developing a model based on our data points is challenging due to the relatively low number of observations and the limited soil variability in our study area. Nevertheless, comparing the distribution of our estimates with similar models adds further validation to our results.\u003c/p\u003e \u003cp\u003eFurthermore, we compared our f\u003csub\u003e0\u003c/sub\u003e estimations with the ones obtained from the AFAD stations situated across the wider Marmara region. Due to the expansive coverage area of these AFAD stations, the variability in their estimations was significantly higher. In fact, their estimations were scattered both around our data points and the pre-existing models mentioned earlier. Consequently, correlating the AFAD estimations with V\u003csub\u003eS30\u003c/sub\u003e posed a considerable challenge. In order to provide a comprehensive overview of our findings, we have included a graphical representation of our data points, existing models, the AFAD estimations, and the f\u003csub\u003e0\u003c/sub\u003e estimated for the BCYCO station in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eThe purpose of this study was to identify and evaluate the site-specific parameters of the B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district of Istanbul, which is located in a region with a high level of seismicity and is thus susceptible to earthquakes. The unique characteristics of the study region, including soil conditions and site amplification characteristics, can influence the intensity and duration of ground motion during an earthquake, making it crucial to understand these factors for predicting the impacts of earthquakes on the region and implementing necessary precautions to reduce damage and loss of life.\u003c/p\u003e \u003cp\u003eTo investigate the site-specific parameters of the B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district, we conducted a field study of measuring seismic ambient vibration and processed the recordings using well-known approaches in the literature. The HVSR method was used to investigate site amplification, and fundamental frequencies and bedrock depths were also examined to gain insight into the soil conditions at the site. The results of these analyses provide valuable information for understanding the site-specific behaviour of the B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district, and can be utilized in ground motion simulations to predict the potential impact of earthquakes on the region.\u003c/p\u003e \u003cp\u003eOur findings demonstrate that the B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district exhibits intermediate to strong site amplification due to the contrast between the poor mechanical characteristics of the alluvial deposits and other softer sediments and the Paleozoic bedrock. The HVSR curves revealed peak frequencies ranging from 1.4 to 2 Hz. In most cases, the amplification factors at these frequencies ranged from 1.5 to 2, with no specific geographical tendency within the study area. The estimated bedrock depths varied from 73 to 108 meters. The following average shearwave estimations also yielded values of 576 to 608 m/s, demonstrating minimal variation.\u003c/p\u003e \u003cp\u003eOur study contributes to a deeper understanding of the seismic hazard in the B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district and provides useful information for future risk assessments. By understanding the site conditions and amplification characteristics, we can more accurately assess the seismic hazard and risk in the study region and take necessary precautions to reduce potential damage and loss of life. The results of our study will be used as input for ground motion simulations to predict the potential impact of earthquakes on the region, which can inform hazard mitigation strategies and help to reduce the potential impact of future earthquakes. Overall, our study highlights the importance of site-specific investigations for improving our understanding of seismic hazard and risk in earthquake-prone regions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to express our sincere gratitude to the Department of Earthquake Engineering at Boğazi\u0026ccedil;i University for their important technical support throughout this project. We particularly wish to thank the technical team for their assistance in placing and recording the ambient vibrations. Their expertise and dedication were essential to the success of this study. We are grateful for the opportunity to work with such a supportive group of professionals.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis work has been supported by UKRI-GCRF in the framework of project \u0026ldquo;Tomorrow\u0026rsquo;s Cities\u0026rdquo;.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and material\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe study is based on the data from the Istanbul Earthquake Rapid Response and Early Warning System operated by the Department of Earthquake Engineering of Boğazi\u0026ccedil;i University\u0026rsquo;s Kandilli Observatory and Earthquake Research Institute and from AFAD.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCode availability\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAcerra C, Aguacil G, Anastasiadis A, Atakan K, Azzara R, Bard PY, Zacharopoulos S (2004) Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations measurements, processing and interpretation. \u003cem\u003eEuropean Commission\u0026ndash;EVG1-CT-2000-00026 SESAME\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBirg\u0026ouml;ren G, \u0026Ouml;zel O, Siyahi B (2009) Bedrock depth mapping of the coast south of Istanbul: comparison of analytical and experimental analyses. \u003cem\u003eTurkish Journal of Earth Sciences, 18(2), 315\u0026ndash;329.\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBonilla LF, Steidl JH, Lindley GT, Tumarkin AG, Archuleta RJ (1997) Site amplification in the San Fernando Valley, California: variability of site-effect estimation using the S-wave, coda, and H/V methods. \u003cem\u003eBulletin of the Seismological Society of America, 87(3), 710\u0026ndash;730.\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCity Scoping (2022) Report for B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece District. 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This study aims to enhance our understanding of seismic hazards in B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece by investigating site-specific parameters. We conducted a comprehensive field study involving seismic ambient vibration measurements at 56 selected locations. The horizontal-to-vertical spectral ratio (HVSR) method was employed to analyze the recorded data, and to obtain fundamental frequencies and approximate bedrock depths. These parameters offer insights into the local soil conditions and site amplification characteristics.\u003c/p\u003e \u003cp\u003eThe findings of this study reveal that the region exhibits intermediate to strong site amplification due to the contrast between alluvial deposits and Paleozoic bedrock. Peak frequencies ranged from 1.4 to 2 Hz, with amplification factors typically ranging from 1.5 to 2. Bedrock depths varied from 73 to 108 meters, and average shear wave velocities to bedrock (V\u003csub\u003eZ\u003c/sub\u003e) showed minimal variation (576 to 608 m/s). Correlations between fundamental frequencies (f\u003csub\u003e0\u003c/sub\u003e) and V\u003csub\u003eS30\u003c/sub\u003e values demonstrate the influence of soil properties on ground motion amplification.\u003c/p\u003e \u003cp\u003eThis study contributes crucial information for seismic hazard assessment and risk reduction in B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece. The results are invaluable for informing ground motion simulations, and and facilitating improved earthquake impact predictions. Understanding site-specific characteristics is essential for enhancing the resilience of earthquake-prone regions like B\u0026uuml;y\u0026uuml;k\u0026ccedil;ekmece district of Istanbul. Overall, this research stresses the significance of site-specific investigations in improving our understanding of seismic hazard and risk.\u003c/p\u003e","manuscriptTitle":"Investigating Site-Specific Parameters for Seismic Hazard Analysis in Büyükçekmece District of Istanbul: Field Study and HVSR Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-10-31 17:56:14","doi":"10.21203/rs.3.rs-3497875/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revisions Needed","date":"2024-10-09T08:23:15+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2023-12-21T11:03:19+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2023-10-26T09:26:09+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2023-10-26T04:32:07+00:00","index":"","fulltext":""},{"type":"submitted","content":"Bulletin of Earthquake Engineering","date":"2023-10-25T08:48:54+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bulletin-of-earthquake-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"beee","sideBox":"Learn more about [Bulletin of Earthquake Engineering](https://www.springer.com/journal/10518)","snPcode":"10518","submissionUrl":"https://submission.nature.com/new-submission/10518/3","title":"Bulletin of Earthquake Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5c73cbd0-eeab-4515-b910-8af40ae95338","owner":[],"postedDate":"October 31st, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-04-07T16:00:11+00:00","versionOfRecord":{"articleIdentity":"rs-3497875","link":"https://doi.org/10.1007/s10518-025-02129-6","journal":{"identity":"bulletin-of-earthquake-engineering","isVorOnly":false,"title":"Bulletin of Earthquake Engineering"},"publishedOn":"2025-04-01 15:57:20","publishedOnDateReadable":"April 1st, 2025"},"versionCreatedAt":"2023-10-31 17:56:14","video":"","vorDoi":"10.1007/s10518-025-02129-6","vorDoiUrl":"https://doi.org/10.1007/s10518-025-02129-6","workflowStages":[]},"version":"v1","identity":"rs-3497875","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3497875","identity":"rs-3497875","version":["v1"]},"buildId":"FbvkV6FR0MCFSLy54lSbu","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}