Hypocenter relocation of the aftershocks of the Poso, Sulawesi (Mw 6.6, May 29, 2017) event using the BMKG network data

On May 29, 2017, an earthquake (Mw 6.6) occurred in the Poso District, central Sulawesi. This earthquake caused damage to houses and infrastructures and several people were seriously injured. About one minute after the mainshock, aftershock sequences occurred around the fault area. Up to June 4, 2017, the BMKG network had recorded 293 aftershock events. We have successfully relocated 238 out of the 293 aftershocks using hypocenter double-difference method. The results indicate improvement in hypocenter location, where the initial earthquakes focal depths fixed at a depth of 10 km have been updated. Our results show that there are two event clusters in a northwest-southeast direction. The first cluster is indicated as aftershocks and the second one is probably the triggered seismicity by the mainshock. A validation through the histogram of travel-time residuals depicts statistically fairly good relocation results, in which the residuals are mostly close to zero.