ISSN 2070-7401 (Print), ISSN 2411-0280 (Online)
Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa


Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2018, Vol. 15, No. 4, pp. 119-127

Joint inversion of the GPS and SAR data for the Gorkha, Nepal earthquake of 25.04.2015

V.O. Mikhailov 1, 2 , E.A. Kiseleva 1 , E.P. Timoshkina 1 , V.B. Smirnov 2, 1 , A.V. Ponomarev 1 , P.N. Dmitriev 1 , I.M. Kartashov 1, 2 , S.A. Khairetdinov 1 , K. Arora 3 , R. Chadha 3 , D. Srinagesh 3 
1 Schmidt Institute of Physics of the Earth RAS, Moscow, Russia
2 Lomonosov Moscow State University, Moscow, Russia
3 CSIR-National Geophysical Research Institute, Hyderabad, India
Accepted: 31.07.2018
DOI: 10.21046/2070-7401-2018-15-4-119-127
We discuss problems of joint inversion of GPS and SAR data using the Gorkha earthquake in Nepal on 25.04.2015 as an example. We applied DInSAR (pair interferogram) technique to the ALOS-2 ScanSAR satellite images. The geometry of the coseismic rupture was constrained by geophysical and geological data. When solving an inverse problem, the misfit of various methods was calculated with weights inversely proportional to the mean square error of each method. For GPS, we used the errors estimated for each station. For SAR interferometry, the error was estimated from the difference of the displacement fields obtained from three pair interferograms which in a total covered the same period of time. The model of the rupture surface contained two inclined planes, which were subdivided into a number of elements. The inverse problem was regularized by the condition of the proximity of the rake angle on each element of the rupture surface to a pre-assigned direction, and also the condition that the module of the displacement vector on each element of some plane is close to the average value over this plane. It is obtained that the main displacements occurred at the Main Himalayan thrust at depths of 6–12 km. Our rupture model agrees well with the available GPS and SAR data and with alternative models based on other methods and other data, as well as with the prevalent ideas on the geodynamics of the study area.
Keywords: satellite geodesy, SAR interferometry, ALOS-2, earthquake, surface of coseismic rupture, numerical modelling, Gorkha, Nepal
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