Analysis of the destructive earthquakes end of 2017 (Mw 6.9) and early 2018 (Mw 6.1) south of West Java, Indonesia

On December 15, 2017, and January 23, 2018, there were destructive earthquakes to the south of West Java, Indonesia, with Mw 6.9 and Mw 6.1, respectively. We have determined the hypocenter location for both mainshocks through re-picking of the Pand S-wave arrival times recorded by the Agency for Meteorology, Climatology, and Geophysics (BMKG) seismic stations in West Java and its vicinity. We have then relocated the aftershocks for both events. We have also conducted focal mechanism analysis to estimate the type of fault slip. Our results show the 2017 and 2018 events occurred in the intra-slab at 108.6 km and 46.5 km depths, respectively. The focal mechanism solution shows a thrust fault type with the strike direction almost perpendicular to the trench for the 2017 event, and it is almost parallel to the trench for the 2018 event.