Preliminary Results of Hypocenter Relocation Analysis in the Sunda Strait, Indonesia, after the 2018 Anak Krakatau Tsunami

The Sunda Strait is located at a change in orientation of the trench resulting in regimes from a frontal subduction in Java into oblique subduction in Sumatra. There are many active faults and volcanoes along this subduction zone. The flank collapse of the Anak Krakatau volcano in the study area caused a tsunami on 22 December 2018. This event increased seismicity in the area. Using the data from the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) from 23 December 2018 to 7 June 2020, we have conducted hypocenter relocation using the Double Difference method. Our preliminary results show that there is a cluster of shallow earthquakes in a southwest-northeast direction probably related to the local active fault in the area. The focal mechanism solutions of selected events show an oblique normal fault type.