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Seismic attenuation tomography of the Northeast Japan arc: Insight into the 2011 Tohoku earthquake ( M w 9.0) and subduction dynamics
Author(s) -
Liu Xin,
Zhao Dapeng,
Li Sanzhong
Publication year - 2014
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2013jb010591
Subject(s) - seismology , geology , intraplate earthquake , subduction , crust , volcanic arc , mantle (geology) , island arc , interplate earthquake , volcano , slip (aerodynamics) , mantle wedge , trench , geophysics , tectonics , chemistry , physics , organic chemistry , layer (electronics) , thermodynamics
Detailed three‐dimensional (3‐D) P and S wave attenuation ( Qp and Qs ) models of the crust and upper mantle under the entire Northeast Japan (Tohoku) arc from the Japan Trench to the Japan Sea coast are determined, for the first time, using a large number of high‐quality t * data measured precisely from P and S wave spectra of local earthquakes. The suboceanic earthquakes used in this work are relocated precisely using sP depth phases. Our results reveal a prominent landward dipping high‐ Q zone representing the subducting Pacific slab, a landward dipping intermediate‐ to high‐ Q zone in the mantle wedge between the Pacific coast and the volcanic front, and significant low‐ Q anomalies in the crust and mantle wedge between the volcanic front and the Japan Sea coast. Prominent high‐ Q patches surrounded by low‐ Q anomalies are revealed in the interplate megathrust zone under the Tohoku fore arc where the great 2011 Tohoku‐oki earthquake ( M w 9.0) occurred. The high‐ Q patches in the megathrust zone generally exhibit large coseismic slips of megathrust earthquakes and large slip deficit on the plate interface. We think that these high‐ Q patches represent asperities in the megathrust zone, whereas the low‐ Q anomalies reflect weakly coupled areas. We also find that the hypocenters of the 2011 Tohoku‐oki interplate earthquakes ( M w > 7.0) are located in areas where Qp , Qs , and Qp/Qs change abruptly. These results suggest that structural heterogeneities in the megathrust zone control the interplate seismic coupling and the nucleation of megathrust earthquakes.