Seismicity around Sunda strait and its surroundings based on hypocenter relocation using 3-D velocity: a preliminary result of relocated hypocenter database construction from the BMKG catalog

Abstract

The relocated hypocenters are very important to study advanced tectonic in one area. The Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) provides a complete earthquake catalog consisting of hypocenter parameter and seismic wave arrival times of P and S phases or only P phase in every seismic station. This study uses the BMKG earthquake catalog from April 2009 to December 2018, in which the earthquakes were recorded by BMKG and international seismic networks. The hypocenters from the BMKG catalog are relocated using a 3-D regional velocity model and applying the teletomoDD method for hypocenter relocation. The results succeed in detecting many tectonic features in Indonesia. The study result will be useful to provide a precise hypocenter for earth scientists around the world who is interesting in a tectonic study in Indonesia. Some tectonic features which are interesting exist in Sunda Strait and its surrounding. The complex structure in Sunda Strait causes the area having high seismic activities. The results show seismic activities in three regions are delineated well. The first seismic region relates to the subduction zone. There is low seismic activity in the Wadati-Benioff zone from 70-120 km. This result is a little different from the previous study. The different result is most likely caused by the use of data and methods that are not the same. The second seismic region associates with graben fault. The last or third seismic region exists beneath Anak Krakatau Volcano relating to the magmatic activity. The last two seismic regions are detected clearly because there are no more fix depths at a depth 10 km after hypocenter relocation.