Hydration-induced faulting as a trigger of intermediate-depth earthquakes

Hydration-induced faulting as a trigger of intermediate-depth 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 Article Hydration-induced faulting as a trigger of intermediate-depth earthquakes Haemyeong Jung, Yong Park This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7726632/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 Subduction zones experience numerous earthquakes at intermediate depths (~50–300 km), despite high pressure at great depths inhibiting brittle behavior in rocks. Several mechanisms for intermediate-depth earthquakes, including dehydration-related processes, have been proposed; however, the exact processes by which brittle failure evolves into large faults and eventually develops into seismic slip remain unclear. Here, we propose the hydration-induced faulting of feldspars as a new mechanism of intermediate-depth earthquakes. We conducted rock-deformation experiments of natural rock containing alkali feldspar and plagioclase in dry and wet environments under pressure and temperature conditions similar to those occurring at subduction zones. We identified faulting associated with the hydration of alkali feldspar and plagioclase, accompanied by ultrafine-grained, weak hydration products, such as illite and smectite. Under high pressure, dynamic weakening resulting from the increased rheological contrast between mechanically weak hydration products and surrounding minerals lead to the localization of strain and development of faults. The increased number of intermediate-depth earthquakes at depths of ~100 km at subduction zones can be attributed to hydration-induced faulting of feldspars under high pressure. This mechanism may also contribute to the seismicity of subducting slabs composed of blueschist and oceanic sediments enriched in alkali feldspar and plagioclase. Earth and environmental sciences/Solid Earth sciences/Seismology Earth and environmental sciences/Solid Earth sciences/Tectonics Earth and environmental sciences/Solid Earth sciences/Petrology Earth and environmental sciences/Solid Earth sciences/Mineralogy 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-7726632","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":529372226,"identity":"3ff019bb-9938-48cc-8e53-c4739fb8d3a6","order_by":0,"name":"Haemyeong Jung","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAt0lEQVRIiWNgGAWjYBACA4YDQLICxj1AtJYzpGkBAsY2UrSYM54xe/h1Xl2ewQHmhx8YztwjrMWy4Yy5sey2w8UGB9iMJRhuFBPhsANnzKQltx1I3HCAwYyB4UMCsVrm1AG1sH8jXovkxwZmoBYeoC03iNJyrEya4djhxJmHeYolEs4Qo+XG4W2SP2rqEvuOt2/88OEYEVoYJA4wMPOAGMxATIwGBgb+BgbGH0SpHAWjYBSMghELANR6P8Xw1ySvAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-4327-4701","institution":"Seoul National University","correspondingAuthor":true,"prefix":"","firstName":"Haemyeong","middleName":"","lastName":"Jung","suffix":""},{"id":529372227,"identity":"56c96146-062d-40d0-a954-281e13741a78","order_by":1,"name":"Yong Park","email":"","orcid":"https://orcid.org/0000-0003-3632-4915","institution":"Seoul National University","correspondingAuthor":false,"prefix":"","firstName":"Yong","middleName":"","lastName":"Park","suffix":""}],"badges":[],"createdAt":"2025-09-27 07:15:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7726632/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7726632/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":97370334,"identity":"2753a7e1-45a2-4b77-9604-985fb3c36ff3","added_by":"auto","created_at":"2025-12-03 16:27:10","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2788748,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscriptandfigures.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7726632/v1_covered_756a545a-aad8-4a14-bc4d-9cb0b6e31f28.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Hydration-induced faulting as a trigger of intermediate-depth 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":"[email protected]","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-7726632/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7726632/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Subduction zones experience numerous earthquakes at intermediate depths (~50–300 km), despite high pressure at great depths inhibiting brittle behavior in rocks. Several mechanisms for intermediate-depth earthquakes, including dehydration-related processes, have been proposed; however, the exact processes by which brittle failure evolves into large faults and eventually develops into seismic slip remain unclear. Here, we propose the hydration-induced faulting of feldspars as a new mechanism of intermediate-depth earthquakes. We conducted rock-deformation experiments of natural rock containing alkali feldspar and plagioclase in dry and wet environments under pressure and temperature conditions similar to those occurring at subduction zones. We identified faulting associated with the hydration of alkali feldspar and plagioclase, accompanied by ultrafine-grained, weak hydration products, such as illite and smectite. Under high pressure, dynamic weakening resulting from the increased rheological contrast between mechanically weak hydration products and surrounding minerals lead to the localization of strain and development of faults. The increased number of intermediate-depth earthquakes at depths of ~100 km at subduction zones can be attributed to hydration-induced faulting of feldspars under high pressure. 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