Source characteristics of 2015 Nepal earthquake

Abstract

In this research, the parameters that characterize the seismic source of Nepal 2015 earthquake (Mw 7.9) were calculated, using a numerical model of teleseismic waveforms inversion. Seismic data were obtained from 57 seismic stations of worldwide network IRIS for epicentral distances between 30° and 90°. To compute the inversion process, 80 seismic signals of P and SH waves are used. The results show a multiple or complex rupture with a unidirectional propagation and directivity to the South-East, the duration of the rupture process was around 90 s. The focal mechanism indicates a thrust fault with an almost horizontal dip of 10° for a shallow depth of 15 km. The area of maximum energy release (or asperity) is concentrated in the center of the rupture geometry and to the West of Kathmandu. The scalar seismic moment is 8.53×1020 Nm, which is equivalent to a moment magnitude of 7.9 Mw. The maximum displacement (or slip) is estimated to 5.2 m. After the earthquake, the city of Kathmandu moved 1.40 m to the South-West and uplifted 0.91 m, according to results obtained.