气候变化领域集成服务门户(CCPortal): Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes

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DOI	10.1029/2020JB019861
	Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes
	Bangs N.L.; Morgan J.K.; Tréhu A.M.; Contreras-Reyes E.; Arnulf A.F.; Han S.; Olsen K.M.; Zhang E.
发表日期	2020
ISSN	21699313
卷号	125 期号:11
英文摘要	The 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. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	accretionary wedge; Chilean margin; earthquake; forearc structure; subduction zone; underplating
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187493
作者单位	Institute for Geophysics, University of Texas at Austin, Austin, TX, United States; Department of Earth, Environmental, and Planetary Sciences, William Marsh Rice University, Houston, TX, United States; College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, United States; Departamento de Geofísica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
推荐引用方式 GB/T 7714	Bangs N.L.,Morgan J.K.,Tréhu A.M.,et al. Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes[J],2020,125(11).
APA	Bangs N.L..,Morgan J.K..,Tréhu A.M..,Contreras-Reyes E..,Arnulf A.F..,...&Zhang E..(2020).Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes.Journal of Geophysical Research: Solid Earth,125(11).
MLA	Bangs N.L.,et al."Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes".Journal of Geophysical Research: Solid Earth 125.11(2020).