TY - JOUR
T1 - Tomography of the source zone of the 2015 M 7.8 Nepal earthquake
AU - Wei, Wei
AU - Zhao, Dapeng
N1 - Funding Information:
We thank the IRIS Data Management Center ( http://www.iris.edu ) for providing the high-quality waveform data used in this study. We are grateful to Dr. E.R. Engdahl for providing his reprocessed ISC data sets ( http://www.isc.ac.uk/ehbbulletin/ ). Prof. K. Koketsu of University of Tokyo kindly permitted us to cite their coseismic slip model ( Fig. 4 b). This work was supported by a Special Fund of State Public Institute for Basic Research (grant IGCEA 1402 ) and grants from JSPS (Kiban-S 23224012 ) and MEXT ( 26106005 ). We appreciate Prof. G. Helffrich (the Editor) and an anonymous reviewer for their thoughtful comments and suggestions which have improved this paper.
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - We conducted P-wave anisotropic tomography beneath Nepal and surrounding areas to clarify the causal mechanism of the 25 April 2015 Nepal earthquake (Mw 7.8) and dynamic processes of the India-Asia collision zone. Our results show that hypocenters of the 2015 Nepal mainshock and the 1833 Nepal earthquake (M 8.0) are located in a zone with a higher P-wave velocity (high-V), and the high-V zone coincides with the coseismic slip area of the 2015 Nepal mainshock. The high-V zone may reflect a strongly coupled patch (i.e., asperity) in the megathrust zone between the subducting Indian plate and the overlying Eurasian plate. This result suggests that the nucleation of the Nepal earthquakes was controlled by structural heterogeneities in the megathrust zone. Significant variations of P-wave velocity anisotropy are revealed across the Himalaya collision belt. The predominant fast P-wave velocity direction is NE-SW beneath northern India, whereas it becomes NW-SE beneath the Himalaya, suggesting that the fossil anisotropy in the Indian plate is overprinted by the ongoing India-Asia collision.
AB - We conducted P-wave anisotropic tomography beneath Nepal and surrounding areas to clarify the causal mechanism of the 25 April 2015 Nepal earthquake (Mw 7.8) and dynamic processes of the India-Asia collision zone. Our results show that hypocenters of the 2015 Nepal mainshock and the 1833 Nepal earthquake (M 8.0) are located in a zone with a higher P-wave velocity (high-V), and the high-V zone coincides with the coseismic slip area of the 2015 Nepal mainshock. The high-V zone may reflect a strongly coupled patch (i.e., asperity) in the megathrust zone between the subducting Indian plate and the overlying Eurasian plate. This result suggests that the nucleation of the Nepal earthquakes was controlled by structural heterogeneities in the megathrust zone. Significant variations of P-wave velocity anisotropy are revealed across the Himalaya collision belt. The predominant fast P-wave velocity direction is NE-SW beneath northern India, whereas it becomes NW-SE beneath the Himalaya, suggesting that the fossil anisotropy in the Indian plate is overprinted by the ongoing India-Asia collision.
KW - 2015 Nepal earthquake
KW - Himalaya collision belt
KW - Seismic anisotropy
KW - Seismic tomography
KW - Seismotectonics
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U2 - 10.1016/j.pepi.2016.01.008
DO - 10.1016/j.pepi.2016.01.008
M3 - Letter
AN - SCOPUS:84959371337
VL - 253
SP - 58
EP - 63
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
SN - 0031-9201
ER -