Slow slip modulates low-frequency seismicity on the San Andreas Fault

Slow slip modulates low-frequency seismicity on the San Andreas Fault | 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 Article Slow slip modulates low-frequency seismicity on the San Andreas Fault Zahra Zali, Patricia Martínez-Garzón, David Mencin, Gregory Beroza This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7317566/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Understanding how slow slip events (SSEs) influence fault behavior is essential for characterizing the spectrum of fault slip and its role in earthquake generation. We develop a deep learning approach to detect SSEs in continuous strainmeter data, enabling the first catalog of short-duration SSEs on the San Andreas Fault near Parkfield based directly on strainmeter observations. These events are coherently observed across three instruments, with supporting evidence from a nearby creepmeter. A location analysis of these events shows that they occur at shallow depths (<4 km), with slip directions consistent with the right-lateral motion of the San Andreas Fault. Short-term SSEs follow a cubic moment–duration scaling law, similar to regular earthquakes and consistent with recent observations of SSEs in subduction zones and with the reinterpretation of the linear scaling as an upper bound on behavior. We find that low-frequency earthquakes (LFEs) increase following the SSEs, suggesting that slow aseismic slip modulates subsequent seismic activity. The detection of such short, subtle SSEs in a transform fault setting fills an observational gap in slow earthquake studies, and underscores the broader relevance of slow slip across tectonic environments. These findings support the view that aseismic and seismic slip processes form a continuum, and that transient deformation in creeping segments can perturb stress in adjacent locked areas, potentially promoting seismic activity. Earth and environmental sciences/Natural hazards Earth and environmental sciences/Solid Earth sciences Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryInformation.pdf Supplementary Information Cite Share Download PDF Status: Under Review 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-7317566","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":499361099,"identity":"0a37a689-44b4-45f1-9501-12345d0e92bc","order_by":0,"name":"Zahra Zali","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA40lEQVRIie2QuwrCMBRAbwnUJeIaUPQXIk6C6Ie4KF0b3FwcvFKIS9VV8GdaAro5O9rFuW5VOmh8gDhE3RxyhpBADic3ABbLX0IwSqH6OLh66X1SHIyX0LjvvlYI/UmpTeOJap15B8rBJsmG7S4UvMjcCPuoxJwTqKz7Ad16AunBnCGglTB3Ozu/HjiSCGQ+NypuKUHVDDkF5tcnJzm+KoPUqFB2rUDGmVawKJWuGA1gLMF4hpzrWVZ0uxGSHswPqy08lWb57ceiYzYciUXB25szGkfq3nO6z/c1+YtisVgslncuyjlISUqrsQMAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-2802-9927","institution":"GFZ German Research Centre for Geosciences","correspondingAuthor":true,"prefix":"","firstName":"Zahra","middleName":"","lastName":"Zali","suffix":""},{"id":499361100,"identity":"004fc0b3-ca5e-45d8-aea3-ecae952dbb3a","order_by":1,"name":"Patricia Martínez-Garzón","email":"","orcid":"","institution":"GFZ German Research Centre for Geosciences","correspondingAuthor":false,"prefix":"","firstName":"Patricia","middleName":"","lastName":"Martínez-Garzón","suffix":""},{"id":499361101,"identity":"700df10e-bce4-4154-a326-2123124f209f","order_by":2,"name":"David Mencin","email":"","orcid":"","institution":"EarthScope Consortium","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"","lastName":"Mencin","suffix":""},{"id":499361102,"identity":"04c2654e-69ea-4d9f-8218-e0de83fc5eda","order_by":3,"name":"Gregory Beroza","email":"","orcid":"https://orcid.org/0000-0002-8667-1838","institution":"Stanford University","correspondingAuthor":false,"prefix":"","firstName":"Gregory","middleName":"","lastName":"Beroza","suffix":""}],"badges":[],"createdAt":"2025-08-07 10:10:52","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7317566/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7317566/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":89068402,"identity":"2a91ac4b-9f06-495c-9dca-cd27c40ca2e4","added_by":"auto","created_at":"2025-08-14 10:47:44","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1358574,"visible":true,"origin":"","legend":"Article File","description":"","filename":"Manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7317566/v1_covered_38d35532-834d-4586-aa79-3f0a53612a61.pdf"},{"id":89067437,"identity":"17178f7d-1a1b-44e5-a539-ee9e593a4f89","added_by":"auto","created_at":"2025-08-14 10:45:02","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2959683,"visible":true,"origin":"","legend":"Supplementary Information","description":"","filename":"SupplementaryInformation.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7317566/v1/b81aa6c1f1412ef02b6e20d4.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Slow slip modulates low-frequency seismicity on the San Andreas Fault","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"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":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7317566/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7317566/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Understanding how slow slip events (SSEs) influence fault behavior is essential for characterizing the spectrum of fault slip and its role in earthquake generation. We develop a deep learning approach to detect SSEs in continuous strainmeter data, enabling the first catalog of short-duration SSEs on the San Andreas Fault near Parkfield based directly on strainmeter observations. These events are coherently observed across three instruments, with supporting evidence from a nearby creepmeter. A location analysis of these events shows that they occur at shallow depths (\u003c4 km), with slip directions consistent with the right-lateral motion of the San Andreas Fault. Short-term SSEs follow a cubic moment–duration scaling law, similar to regular earthquakes and consistent with recent observations of SSEs in subduction zones and with the reinterpretation of the linear scaling as an upper bound on behavior. We find that low-frequency earthquakes (LFEs) increase following the SSEs, suggesting that slow aseismic slip modulates subsequent seismic activity. The detection of such short, subtle SSEs in a transform fault setting fills an observational gap in slow earthquake studies, and underscores the broader relevance of slow slip across tectonic environments. 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