{"paper_id":"488f9ba3-ec25-4b93-ab99-a1b43e11ebdf","body_text":"Global investigation of foreshock acceleration prior to large earthquakes | 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 Physical Sciences - Article Global investigation of foreshock acceleration prior to large earthquakes Tomoaki Nishikawa, Kai Koyama This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8343941/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Predicting large earthquakes remains one of the most important yet unresolved challenges in geoscience1,2,3. Accelerating aseismic slip (preslip) and associated accelerating foreshock activity have long been discussed as possible precursory phenomena preceding large earthquakes4–11. Previous studies have reported that many large earthquakes worldwide were preceded by accelerating foreshock sequences, suggesting a potential for earthquake forecasting12,13. However, how frequently such acceleration occurs and whether it is unique to the periods preceding large earthquakes remain unclear. Here we statistically analyse seismic activity preceding large earthquakes worldwide, showing that significant foreshock acceleration is very rare and not unique to large earthquakes. We extend the epidemic-type aftershock-sequence model with an acceleration term based on laboratory and simulation results14,15 to quantitatively evaluate the number and characteristic timescale of foreshocks, revealing that such acceleration occurs before only 3–4% of large earthquakes. Comparisons with randomly selected seismic activity and synthetic earthquake catalogs demonstrate that the observed acceleration cannot be explained by aftershock cascades, implying that it results from aseismic processes, yet it is not regarded as unique to large earthquakes. These findings reveal the limitations of the preslip-based forecasting framework supported by theory, observation, and experiments, highlighting the need for a new paradigm in earthquake forecasting. Earth and environmental sciences/Solid Earth sciences/Seismology Earth and environmental sciences/Natural hazards Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-8343941\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Physical Sciences - Article\",\"associatedPublications\":[],\"authors\":[{\"id\":559283304,\"identity\":\"e7b83de9-5386-4cfc-9b49-0231e191f397\",\"order_by\":0,\"name\":\"Tomoaki Nishikawa\",\"email\":\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABSElEQVRIie2RP0vDQBTA3/Hgshy6RoT4FVIO2oolfpULGVwSXAsVGym0S7FrQKFfQb/ByUGzBFwzVoXOgULpJJ5GaRIacBTJb3rvcT/enwNoaPiLIFAQcpfbFFBCVqgACesU/FGoIJGusDoFtAJFRb+1kRWVCh3DWC2XiePOwsOn17Tv8AMAvu4lyjo3QmrClQN4V2pzOmIdW6SeG0lE7ideWzcV3E8VZ0xqZeEBuS9uBrZi1BQZBqFEehyMsfc5p+dnyp2alxsTqAQSibJirLQyDOa5MtQKCVX3SxG6y/seBdqmSFXwkCtKD4ZkBOm3QsZ7FKaVJB4+KuR6l5hTpEimyQVnicSue+ux6i7P8epouxhwK755efP7g9Z8Mltn28WZZUxCkmYbx2qVL7YDy8EoT/RIrBXV/FCF6114Yv5OaWhoaPivfACnuHRmiRg4bQAAAABJRU5ErkJggg==\",\"orcid\":\"\",\"institution\":\"Kyoto University\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Tomoaki\",\"middleName\":\"\",\"lastName\":\"Nishikawa\",\"suffix\":\"\"},{\"id\":559283305,\"identity\":\"4371d2b5-42b4-465a-a11b-68a94c4c8113\",\"order_by\":1,\"name\":\"Kai Koyama\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kyoto University\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Kai\",\"middleName\":\"\",\"lastName\":\"Koyama\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2025-12-12 09:22:33\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-8343941/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-8343941/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":99792891,\"identity\":\"9c3a4da0-11ea-4068-a46c-ce3d61de2a51\",\"added_by\":\"auto\",\"created_at\":\"2026-01-08 13:28:16\",\"extension\":\"pdf\",\"order_by\":1,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":1248903,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"NatureManuscriptKoyamaNishikawa.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8343941/v1_covered_dbe688b1-c0d2-4c89-8fd7-c62073df20c7.pdf\"}],\"financialInterests\":\"There is \\u003cb\\u003eNO\\u003c/b\\u003e Competing Interest.\",\"formattedTitle\":\"Global investigation of foreshock acceleration prior to large earthquakes\",\"fulltext\":[],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":false,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":true,\"hideJournal\":true,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":true,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":true,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true},\"keywords\":\"\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-8343941/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-8343941/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"Predicting large earthquakes remains one of the most important yet unresolved challenges in geoscience1,2,3. 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