文章基本信息

标题：Possible large near-trench slip during the 2011 M w 9.0 off the Pacific coast of Tohoku Earthquake
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作者：Thorne Lay ; Charles J. Ammon ; Hiroo Kanamori 等
期刊名称：Earth, Planets and Space
电子版ISSN：1880-5981
出版年度：2011
卷号：63
期号：7
页码：687-692
DOI：10.5047/eps.2011.05.033
出版社：Springer Verlag
摘要：The 11 March 2011 off the Pacific coast of Tohoku ( M w 9.0) Earthquake ruptured a 200 km wide megathrust fault, with average displacements of ~15–20 m.Early estimates of the co-seismic slip distribution using seismic, geodetic and tsunami observations vary significantly in the placement of slip, particularly in the vicinity of the trench.All methods have difficulty resolving the up-dip extent of rupture; onshore geodetic inversions have limited sensitivity to slip far offshore, seismic inversions have instabilities in seismic moment estimation as subfault segments get very shallow, and tsunami inversions average over the total region of ocean bottom uplift.Seismic wave estimates depend strongly on the velocity structure used in the model, which affects both seismic moment estimation and inferred mapping to slip.We explore these ideas using a least-squares inversion of teleseismic P -waves that yields surprisingly large fault displacements (up to ~60 m) at shallow depth under a protrusion of the upper plate into the trench.This model provides good prediction of GPS static displacements on Honshu.We emphasize the importance of poorly-constrained rigidity variations with depth for estimating fault displacement near the trench.The possibility of large slip at very shallow depth holds implications for up-dip strain accumulation and tsunamigenic earthquake potential of megathrusts elsewhere. Key words 2011 Tohoku Earthquake megathrust faults subduction zones earthquake rupture process tsunami earthquakes.
关键词：2011 Tohoku Earthquake ;megathrust faults ;subduction zones ;earthquake rupture process ;tsunami earthquakes