Tectonic features beneath Bali and Nusa Tenggara islands revealed from seismic Tomography of P-wave: A preliminary result

Bali and Nusa Tenggara islands have a complex tectonic setting in Indonesia. Seismic activities in that area are affected by the subduction zone, the Flores backarc thrust, local faults, and volcanic activities. In this study, we show tectonic features in that area from vertical sections revealed from seismic tomography of P-wave. Relocated earthquake catalog of BMKG in that area is utilized to compute seismic tomography. Our seismic data resolution is limited at a maximum depth of 420 km beneath Lombok island. The results show tectonic features could be seen clearly in vertical sections passing Agung, Rinjani, and Kelimutu volcanoes. All tectonic features in three vertical sections are associated with the subduction zone (high velocity), magma supplying from the partial melting zone (low velocity), and the Flores backarc thrust (contact zone between low and high velocity). One vertical section beneath Flores island shows a partial melting zone occurs at a depth more than 100 km, and two other vertical sections beneath Bali and Lombok islands occur at a depth shallower than 100 km. This study is beneficial for earthquake disaster mitigation, especially in updating tectonic features based on regional tomographic seismic imaging in that area.