THE COSEISMIC SOURCE SLIP AND COULOMB STRESS TRIGGERING OF 2015 NEPAL GORKHA MW7.9 AND KODARIMW7.3 EARTHQUAKE BASED ON InSAR MEASUREMENTS |
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| Authors: | ZHANG Ying-feng ZHANG Guo-hong SHAN Xin-jian WEN Shao-yan |
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| Institution: | 1. China University of PetroleumEast China, School of Geoscience, Qingdao 266580, China;2. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;3. Earthquake Administration of Xinjiang Uygur Autonomous Region, Urmuqi 830002, China |
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| Abstract: | According to the structure of the Himalayan orogenic belt, a low-angle antilistric thrust-slip fault model is used to simulate the ramp on the rupture portion of the Main Himalayan Fault. Based on descending Alos -2 and Sentinal -1 data, we invert for the coseismic slip models of the Gorkha earthquake and its largest aftershock, Kodari earthquake. In contrast to the inversion using Alos -2 or Sentinal -1 separately, the joint inversion of both data sets has stronger constraint for the deep slip and can obtain more details in Gorkha earthquake. The rupture depth obtained by joint inversion can be as deep as 24km underground, cutting across the locking line to the transition of locked and the creeping zone. The largest slip is as large as 4.5m appearing 17km underground and the dip angle is between 3°and 10°. Gorkha and Kodari earthquakes have the similar focal mechanisms, both of which are mainly thrusting, and yet some right-lateral slip component in Gorkha earthquake. The inversion results reveal that slip models of the Nepal mainshock and its largest aftershock are complementary in space and the Kodari earthquake occurs in the gaps of slip in Gorkha earthquake. The epicenter of the Kodari earthquake is just right in the transitive zone of the positive and negative Coulomb stress change, where the Coulomb stress change can reach 0.4MPa. We thus argue that Kodari earthquake has been triggered by the Gorkha earthquake. |
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| Keywords: | Nepal GorkhaMW7 9 earthquake coseismic slip inversion rupture model stress triggering |
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