Seismic Site Classification and Correlation Between SPT N-Value and Shear Wave Velocity in The Niger Delta Region

Seismic Site Classification and Correlation Between SPT N-Value and Shear Wave Velocity in The Niger Delta Region | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Seismic Site Classification and Correlation Between SPT N-Value and Shear Wave Velocity in The Niger Delta Region Charles Kennedy This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4457298/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 2 You are reading this latest preprint version Abstract This study investigates seismic site classification and the empirical correlations between SPT blow counts (N-values) and shear wave velocity (Vs) in the Niger Delta region of Nigeria. Accurate site classification is vital for evaluating seismic ground response and liquefaction potential in earthquake-prone areas like the Niger Delta. To overcome the challenges of costly and time-consuming direct geophysical measurements of shear wave velocity, the study utilizes the SPT as an in-situ test to indirectly estimate Vs through empirical correlations. The research involves subsurface exploration at two sites in Agudama Town, Bayelsa State. SPT borings were conducted to depths of 30m, collecting disturbed soil samples at 1.5m intervals and undisturbed samples from deeper cohesive layers. Laboratory testing was performed to classify the soils according to the Unified Soil Classification System and determine key engineering properties. Grain size analyses revealed a transition from sandy soils near the surface to silty clay with increasing depth, attributed to natural sorting processes in deltaic sediments. Consistency limits indicated low to intermediate plasticity soils in the upper layers, transitioning to high plasticity at greater depths. Downhole geophysical tests directly measured Vs profiles, which, combined with SPT blow counts, facilitated site classification based on the NEHRP and Eurocode 8 systems. Additionally, one-dimensional equivalent linear site response analysis estimated amplification factors across various strains and periods, predicting peak amplifications of 0.4 to 0.7 seconds that aligned with the subsurface conditions. Empirical correlations were established to relate SPT-N values to Vs, achieving R2 values exceeding 0.90. Predictive models for liquefaction potential factor of safety demonstrated good agreement with observed trends. These findings offer valuable insights into subsurface conditions and establish initial predictive tools for seismic hazard assessment in the soft deltaic soils of the Niger Delta region. Further studies are necessary to expand the database, refine correlations and classifications, and account for geological variability in this seismically active area. These investigations will enhance the understanding of the region's subsurface characteristics and improve the accuracy of seismic hazard assessments. Seismic site classification Liquefaction Potential Shear wave velocity Standard penetration test Niger Delta Soils Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Submission checks completed at journal 29 May, 2024 First submitted to journal 21 May, 2024 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. 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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-4457298","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":308061421,"identity":"d90656a2-24dc-4061-82d2-7432f90bc742","order_by":0,"name":"Charles Kennedy","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8UlEQVRIiWNgGAWjYBACgwNAgrGBgYGPvYGBGSYKEsAJDBugKth4DhCpxRimgk0igUgtZuy9Bxh+7rDLZ5N8Y/i5oMKGgb+9gU1yBh4tNjznEhh7zyRbtknnGEvPOJPGIHHmAJvkBnxaJHIMmBnbmA3YpHMMpHnbDjMYSCSwST7A5zD5NyAt9QZskmeMfxOlxViCB6TlsAGbBI8ZwhZ8DjPsyTFg7G07bsDGk1ZmzXMmjUfizMFmS3zeNzh+xoDhZ1u1AT/74c23eSps5Pjbmw/e7MGjBQjYf0BoDgMQyUMgVlC1PiBW5SgYBaNgFIwwAADfkUF/ybauiwAAAABJRU5ErkJggg==","orcid":"","institution":"Kenule Beeson Saro-Wiwa Polytechnic","correspondingAuthor":true,"prefix":"","firstName":"Charles","middleName":"","lastName":"Kennedy","suffix":""}],"badges":[],"createdAt":"2024-05-21 23:25:01","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4457298/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4457298/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":58082294,"identity":"16773931-0015-4d08-b29d-bd0a6cb54030","added_by":"auto","created_at":"2024-06-11 01:29:38","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":537925,"visible":true,"origin":"","legend":"","description":"","filename":"SeismicSiteClassificationandCorrelationBetweenSPTNValueandShearWaveVelocityinTheNigerDeltaRegion.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4457298/v1_covered_471c1301-25f3-4c17-a81a-93fad0243e40.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Seismic Site Classification and Correlation Between SPT N-Value and Shear Wave Velocity in The Niger Delta Region","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-oceans","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Oceans](https://www.springer.com/journal/44289)","snPcode":"44289","submissionUrl":"https://submission.nature.com/new-submission/44289","title":"Discover Oceans","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Seismic site classification, Liquefaction Potential, Shear wave velocity, Standard penetration test, Niger Delta Soils","lastPublishedDoi":"10.21203/rs.3.rs-4457298/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4457298/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigates seismic site classification and the empirical correlations between SPT blow counts (N-values) and shear wave velocity (Vs) in the Niger Delta region of Nigeria. Accurate site classification is vital for evaluating seismic ground response and liquefaction potential in earthquake-prone areas like the Niger Delta. To overcome the challenges of costly and time-consuming direct geophysical measurements of shear wave velocity, the study utilizes the SPT as an in-situ test to indirectly estimate Vs through empirical correlations. The research involves subsurface exploration at two sites in Agudama Town, Bayelsa State. SPT borings were conducted to depths of 30m, collecting disturbed soil samples at 1.5m intervals and undisturbed samples from deeper cohesive layers. Laboratory testing was performed to classify the soils according to the Unified Soil Classification System and determine key engineering properties. Grain size analyses revealed a transition from sandy soils near the surface to silty clay with increasing depth, attributed to natural sorting processes in deltaic sediments. Consistency limits indicated low to intermediate plasticity soils in the upper layers, transitioning to high plasticity at greater depths. Downhole geophysical tests directly measured Vs profiles, which, combined with SPT blow counts, facilitated site classification based on the NEHRP and Eurocode 8 systems. Additionally, one-dimensional equivalent linear site response analysis estimated amplification factors across various strains and periods, predicting peak amplifications of 0.4 to 0.7 seconds that aligned with the subsurface conditions. Empirical correlations were established to relate SPT-N values to Vs, achieving R2 values exceeding 0.90. Predictive models for liquefaction potential factor of safety demonstrated good agreement with observed trends. These findings offer valuable insights into subsurface conditions and establish initial predictive tools for seismic hazard assessment in the soft deltaic soils of the Niger Delta region. Further studies are necessary to expand the database, refine correlations and classifications, and account for geological variability in this seismically active area. 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