The seismic cycle at subduction thrusts: Insights from seismo-thermo-mechanical models

Handle URI:
http://hdl.handle.net/10754/552162
Title:
The seismic cycle at subduction thrusts: Insights from seismo-thermo-mechanical models
Authors:
van Dinther, Y.; Gerya, T. V.; Dalguer, L. A.; Mai, Paul Martin ( 0000-0002-9744-4964 ) ; Morra, G.; Giardini, D.
Abstract:
The underestimation of the size of recent megathrust earthquakes illustrates our limited understanding of their spatiotemporal occurrence and governing physics. To unravel their relation to associated subduction dynamics and long-term deformation, we developed a 2-D continuum viscoelastoplastic model that uses an Eulerian-Lagrangian finite difference framework with similar on- and off-fault physics. We extend the validation of this numerical tool to a realistic subduction zone setting that resembles Southern Chile. The resulting quasi-periodic pattern of quasi-characteristic M8–M9 megathrust events compares quantitatively with observed recurrence and earthquake source parameters, albeit at very slow coseismic speeds. Without any data fitting, surface displacements agree with GPS data recorded before and during the 2010 M8.8 Maule earthquake, including the presence of a second-order flexural bulge. These surface displacements show cycle-to-cycle variations of slip deficits, which overall accommodate ∼5% of permanent internal shortening. We find that thermally (and stress) driven creep governs a spontaneous conditionally stable downdip transition zone between temperatures of ∼350°C and ∼450°C. Ruptures initiate above it (and below the forearc Moho), propagate within it, interspersed by small intermittent events, and arrest below it as ductile shearing relaxes stresses. Ruptures typically propagate upward along lithological boundaries and widen as pressures drop. The main thrust is constrained to be weak due to fluid-induced weakening required to sustain regular subduction and to generate events with natural characteristics (fluid pressures of ∼75–99% of solid pressures). The agreement with a range of seismological, geodetic, and geological observations demonstrates the validity and strength of this physically consistent seismo-thermo-mechanical approach.
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Citation:
The seismic cycle at subduction thrusts: Insights from seismo-thermo-mechanical models 2013, 118 (12):6183 Journal of Geophysical Research: Solid Earth
Journal:
Journal of Geophysical Research: Solid Earth
Issue Date:
Dec-2013
DOI:
10.1002/2013JB010380
Type:
Article
ISSN:
21699313
Additional Links:
http://doi.wiley.com/10.1002/2013JB010380
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorvan Dinther, Y.en
dc.contributor.authorGerya, T. V.en
dc.contributor.authorDalguer, L. A.en
dc.contributor.authorMai, Paul Martinen
dc.contributor.authorMorra, G.en
dc.contributor.authorGiardini, D.en
dc.date.accessioned2015-05-04T16:25:23Zen
dc.date.available2015-05-04T16:25:23Zen
dc.date.issued2013-12en
dc.identifier.citationThe seismic cycle at subduction thrusts: Insights from seismo-thermo-mechanical models 2013, 118 (12):6183 Journal of Geophysical Research: Solid Earthen
dc.identifier.issn21699313en
dc.identifier.doi10.1002/2013JB010380en
dc.identifier.urihttp://hdl.handle.net/10754/552162en
dc.description.abstractThe underestimation of the size of recent megathrust earthquakes illustrates our limited understanding of their spatiotemporal occurrence and governing physics. To unravel their relation to associated subduction dynamics and long-term deformation, we developed a 2-D continuum viscoelastoplastic model that uses an Eulerian-Lagrangian finite difference framework with similar on- and off-fault physics. We extend the validation of this numerical tool to a realistic subduction zone setting that resembles Southern Chile. The resulting quasi-periodic pattern of quasi-characteristic M8–M9 megathrust events compares quantitatively with observed recurrence and earthquake source parameters, albeit at very slow coseismic speeds. Without any data fitting, surface displacements agree with GPS data recorded before and during the 2010 M8.8 Maule earthquake, including the presence of a second-order flexural bulge. These surface displacements show cycle-to-cycle variations of slip deficits, which overall accommodate ∼5% of permanent internal shortening. We find that thermally (and stress) driven creep governs a spontaneous conditionally stable downdip transition zone between temperatures of ∼350°C and ∼450°C. Ruptures initiate above it (and below the forearc Moho), propagate within it, interspersed by small intermittent events, and arrest below it as ductile shearing relaxes stresses. Ruptures typically propagate upward along lithological boundaries and widen as pressures drop. The main thrust is constrained to be weak due to fluid-induced weakening required to sustain regular subduction and to generate events with natural characteristics (fluid pressures of ∼75–99% of solid pressures). The agreement with a range of seismological, geodetic, and geological observations demonstrates the validity and strength of this physically consistent seismo-thermo-mechanical approach.en
dc.relation.urlhttp://doi.wiley.com/10.1002/2013JB010380en
dc.rightsArchived with thanks to Journal of Geophysical Research: Solid Earthen
dc.titleThe seismic cycle at subduction thrusts: Insights from seismo-thermo-mechanical modelsen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalJournal of Geophysical Research: Solid Earthen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionSwiss Seismological Service; ETH Zürich; Zürich Switzerlanden
dc.contributor.institutionInstitute of Geophysics; ETH Zürich; Zürich Switzerlanden
dc.contributor.institutionSwiss Seismological Service; ETH Zürich; Zürich Switzerlanden
dc.contributor.institutionSchool of Geosciences, Department of Physics; University of Louisiana; Lafayette Louisiana USAen
dc.contributor.institutionInstitute of Geophysics; ETH Zürich; Zürich Switzerlanden
kaust.authorMai, Paul Martinen
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