Joint inversion of teleseismic and co-seismic InSAR data for the rupture process of the 2016 Kumamoto earthquake in Japan

On April 15, 2016, a disastrous earthquake struck Kumamoto county in Japan. Aiming to further understand the complexity of the earthquake rupture in detail, we conduct a joint inversion of teleseismic waveforms and co-seismic InSAR data for the spatio-temporal rupture process of this earthquake. The results show that, the whole process lasted for about 25 s and released scalar moment up to 6.03×10¹⁹ N·m, corresponding to moment magnitude M_W7.1. The major co-seismic slip distribution was centered in shallow region, and it was dominated by dextral strike. But the rupture had strong normal characteristics in the range of 0−5 km along the dip direction. The maximum co-seismic slip is about 4.9 m, and the major rupture patch was about 5−10 km away from the initial rupture point opposite to the strike direction. In the early stage （0−7 s）, it ruptured toward to the shallow region along the dip direction, and ruptured bilaterally along strike direction; about 7 s later, it ruptured toward to the northeast opposite to the strike direction. The joint inversion results suggest that the Kumamoto earthquake may rupture to the earth surface.