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dc.contributor.authorRoland, Emily C.  Concept link
dc.contributor.authorLizarralde, Daniel  Concept link
dc.contributor.authorMcGuire, Jeffrey J.  Concept link
dc.contributor.authorCollins, John A.  Concept link
dc.date.accessioned2012-12-18T19:19:55Z
dc.date.available2014-10-22T08:57:23Z
dc.date.issued2012-11-17
dc.identifier.citationJournal of Geophysical Research 117 (2012): B11102en_US
dc.identifier.urihttps://hdl.handle.net/1912/5640
dc.descriptionAuthor Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): B11102, doi:10.1029/2012JB009422.en_US
dc.description.abstractMid-ocean ridge transform faults (RTFs) vary strongly along strike in their ability to generate large earthquakes. This general observation suggests that local variations in material properties along RTFs exert a primary control on earthquake rupture dynamics. We explore these relationships by examining the seismic structure of two RTFs that have distinctly different seismic coupling. We determine the seismic velocity structure at the Gofar and Quebrada faults on the East Pacific Rise (EPR) using P wave traveltime tomography with data from two active-source wide-angle refraction lines crossing the faults. We image low-velocity zones (LVZs) at both faults, where P wave velocities are reduced by as much as 0.5–1.0 km/s (~10–20%) within a several kilometer wide region. At the Gofar fault, the LVZ extends through the entire crust, into the seismogenic zone. We rule out widespread serpentinization as an explanation for the low velocities, owing to the lack of a corresponding signal in the locally measured gravity field. The reduced velocities can be explained if the plate boundary region is composed of fault material with enhanced fluid-filled porosity (1.5–8%). Local seismic observations indicate that the high-porosity region lies within a ~10 km long portion of the fault that fails in large swarms of microearthquakes and acts as a barrier to the propagation of large (M ~ 6.0) earthquakes. Tomographic images of fault structure combined with observed earthquake behavior suggest that EPR transform segments capable of generating large earthquakes have relatively intact gabbro within the seismogenic zone, whereas segments that slip aseismically or via earthquake swarms are composed of highly fractured, ≥2 km wide damage zones that extend throughout the crust.en_US
dc.description.sponsorshipThe material presented here is based upon work supported by the National Science Foundation Division of Ocean Sciences (OCE) grant 0242117, Division of Earth Sciences (EAR) grant 0943480, and the W. M. Keck Foundation.en_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherAmerican Geophysical Unionen_US
dc.relation.urihttps://doi.org/10.1029/2012JB009422
dc.subjectFault structureen_US
dc.subjectMarine seismologyen_US
dc.subjectRupture dynamicsen_US
dc.subjectTomographyen_US
dc.subjectTransform faulten_US
dc.titleSeismic velocity constraints on the material properties that control earthquake behavior at the Quebrada-Discovery-Gofar transform faults, East Pacific Riseen_US
dc.typeArticleen_US
dc.description.embargo2013-05-17en_US
dc.identifier.doi10.1029/2012JB009422


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