Frequency-dependent rupture process,stress change,and seismogenic mechanism of the 25 April 2015 Nepal Gorkha Mw 7.8 earthquake |
| |
| Authors: | JiuXun Yin HuaJian Yao HongFeng Yang Jing Liu WeiZe Qin HaiJiang Zhang |
| |
| Affiliation: | 1.Laboratory of Seismology and Physics of Earth’s Interior & School of Earth and Space Sciences,University of Science and Technology of China,Hefei,China;2.Earth System Science Programme, Faculty of Science,Chinese University of Hong Kong,Shatin, NT, Hong Kong,China;3.National Geophysical Observatory at Mengcheng,University of Science and Technology of China,Mengcheng,China;4.State Key Laboratory of Earthquake Dynamics, Institute of Geology,China Earthquake Administration,Beijing,China |
| |
| Abstract: | On 25 April 2015, an M w 7.8 earthquake occurred on the Main Himalaya Thrust fault with a dip angle of ~ 7° about 77 km northwest of Kathmandu, Nepal. This Nepal Gorkha event is the largest one on the Himalayan thrust belt since 1950. Here we use the compressive sensing method in the frequency domain to track the seismic radiation and rupture process of this event using teleseismic P waves recorded by array stations in North America. We also compute the distribution of static shear stress changes on the fault plane from a coseismic slip model. Our results indicate a dominant east-southeastward unilateral rupture process from the epicenter with an average rupture speed of ~3 km s?1. Coseismic radiation of this earthquake shows clear frequency-dependent features. The lower frequency (0.05–0.3 Hz) radiation mainly originates from large coseismic slip regions with negative coseismic shear stress changes. In comparison, higher frequency (0.3–0.6 Hz) radiation appears to be from the down-dip part around the margin of large slip areas, which has been loaded and presents positive coseismic shear stress changes. We propose an asperity model to interpret this Nepal earthquake sequence and compare the frequency-dependent coseismic radiation with that in subduction zones. Such frequency-dependent radiation indicates the depth-varying frictional properties on the plate interface of the Nepal section in the main Himalaya thrust system, similar to previous findings in oceanic subduction zones. Our findings provide further evidence of the spatial correlation between changes of static stress status on the fault plane and the observed frequency-dependent coseismic radiation during large earthquakes. Our results show that the frequency-dependent coseismic radiation is not only found for megathrust earthquakes in the oceanic subduction environment, but also holds true for thrust events in the continental collision zone. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
