Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes

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dc.citation.articleNumbere2020JB019861en_US
dc.citation.issueNumber11en_US
dc.citation.journalTitleJournal of Geophysical Research: Solid Earthen_US
dc.citation.volumeNumber125en_US
dc.contributor.authorBangs, N.L.en_US
dc.contributor.authorMorgan, J.K.en_US
dc.contributor.authorTréhu, A.M.en_US
dc.contributor.authorContreras‐Reyes, E.en_US
dc.contributor.authorArnulf, A.F.en_US
dc.contributor.authorHan, S.en_US
dc.contributor.authorOlsen, K.M.en_US
dc.contributor.authorZhang, E.en_US
dc.date.accessioned2020-12-16T22:09:03Zen_US
dc.date.available2020-12-16T22:09:03Zen_US
dc.date.issued2020en_US
dc.description.abstractThe south central Chilean margin regularly produces many of the world's largest earthquakes and tsunami, including the 2010 Mw 8.8 Maule and 1960 Mw 9.5 Valdivia events. In 2017, we acquired seismic reflection data along ~1,000 km of the margin using the R/V Langseth's 15 km long receiver array and 108.2 l (6,600 in3) seismic source to image structures associated with these ruptures. We focus on the Valdivia segment with the largest coseismic slip (~40 m). The outer 40 km of the forearc is an accretionary wedge constructed primarily of stacked sedimentary packages with irregular lengths and thicknesses and little along‐strike continuity. Forearc structures indicate that the accretionary wedge grows primarily through basal accretion of the downgoing trench fill. The décollement propagates along a weak boundary near the top of the trench fill but occasionally branches downward into the underthrust sediment along bedding horizons, peeling off slices that are underplated to the forearc. The shallow décollement level and the rarity of underplating events allow most of the trench sediment to subduct. As a result, only ~30% of the incoming sediment has been accreted since the Early Pliocene. This implies that, on average, ~1 km of sediment must subduct beyond the outer forearc, an inference that is supported by our seismic images. We propose that the thickness and great downdip and along‐strike extent of the underthrust layer, which separates the megathrust from the underlying roughness of the igneous ocean crust, ensures a smooth broad zone of strong coupling that generates the world's largest earthquakes and tsunami.en_US
dc.identifier.citationBangs, N.L., Morgan, J.K., Tréhu, A.M., et al.. "Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes." <i>Journal of Geophysical Research: Solid Earth,</i> 125, no. 11 (2020) Wiley: https://doi.org/10.1029/2020JB019861.en_US
dc.identifier.doihttps://doi.org/10.1029/2020JB019861en_US
dc.identifier.urihttps://hdl.handle.net/1911/109750en_US
dc.language.isoengen_US
dc.publisherWileyen_US
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.en_US
dc.titleBasal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakesen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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