Fast inversion of rupture process of the 14 April 2010 Yushu,Qinghai,earthquake

Four results of the rupture process of 14 April 2010 Yushu, Qinghai, earthquake, obtained by inverting the broadband seismic data of Global Seismographic Network （GSN） based on the inversion method of earthquake rupture process, were compared and discussed. It is found that the Yushu earthquake has several basic characteristics as follows： 1 There exist two principal sub-events which correspond to two slip-concentrated patches being located near the hypocenter and to the southeast of the epicenter. The rupture of the slip-concentrated patch to the southeast of the epicenter broke though the ground surface; 2 The peak slip and peak slip-rate are about 2.1 m and 1.1 m/s, respectively, indicating that the Yushu earthquake is an event with large slip-rate on the fault plane; 3 Overall the Yushu earthquake is a unilateral rupture event with the rupture mainly propagating southeastward. The strong focusing of the seismic energy in the southeast of the epicenter due to the ＂seismic Doppler effect＂ reasonably accounts for the tremendous damage in the Yushu city.

Source rupture process of the 2015 Gorkha, Nepal Mw7.9 earthquake and its tectonic implications

On 25 April, 2015, an Mw7.9 earthquake occurred in Nepal, which caused great economic loss and casualties. However, almost no surface ruptures were observed. Therefore, in order to interpret the phenomenon, we study the rupture process of the earthquake to seek answers. Inversion of teleseismic body-wave data is applied to estimate the rupture process of the 2015 Nepal earthquake. To obtain stable solutions, smoothing and non-negative constraints are introduced. 48 teleseismic stations with good coverage are chosen. Finite fault model is established with length and width of 195 km and 150 km, and we set the initial seismic source parameters referring to CMT solutions. Inversion results indicate that the focal mechanism of this earthquake is a thrust fault type, and the strike, dip and rake angle are in accordance with CMT results. The seismic moment is 0.9195 ×10^（21）Nm（Mw7.9）, and source duration is about 70s. The rupture nucleated near the hypocenter and then propagated along the dip direction to the southeast, and the maximum slip amounts to 5.2 m. Uncertainties on the amount of slip retrieved by different inversion methods still exist, the overall characteristics are inconsistent. The lack of shallow slip during the 2015 Gorkha earthquake implies future seismic hazard and this region should be paid more attention to.

Numerical simulation for 1975 Haicheng and 1999 Xiuyan earthquake processes by DDA+FEM

In this paper, using discontinuous deformation analysis, we simulate numerically the processes of the 1975 Haicheng earthquake and the 1999 Xiuyan earthquake in the tectonic environment of North China where blocks restrict each other by DDA+FEM. Based on the research on the distribution of foreshocks and recent aftershocks of Xiuyan earthquake and the results from our study and other study on Haicheng earthquake, we present a tectonic block model of Haicheng and Xiuyan earthquakes. The results from numerical simulation include the variation of principal stress field released by these two earthquakes, contour patterns of maximum shear stress change, variation patterns of displacement vectors before and after the earthquakes and variation of the earthquake fault slip with time, which agree basically with the focal mechanisms, macroscopic isoseismal and horizontal displacement characters from observations.

Rupture Process of the M_s 7.0 Lushan Earthquake Determined by Joint Inversion of Local Static GPS Records, Strong Motion Data, and Teleseismograms

On April 20, 2013, an M_s 7.0 earthquake struck Lushan County in Sichuan Province, China, and caused serious damage to the source region. We investigated the rupture process of the M_s7.0 Lushan earthquake by jointly inverting waveforms of teleseismic P waveforms and local strong motion records as well as static GPS observations. The inverted results indicate that the rupture of this earthquake was dominated by the failure of an asperity with a triangular shape and that the main shock was dominated by thrust slip. The earthquake released a total seismic moment of 1.01× 10^（19）Nm, with 92% of it being released during the first 11 s. The rupture had an average slip of 0.9 m and produced an average stress drop of 1.8 MPa. Compared with our previous work that was based mainly on a unique dataset, this joint inversion result is more consistent with field observations and the distribution of aftershock zones.