Crustal Structure Beneath KLNI Station in Lombok Island Based on Teleseismic Receiver Function

Abstract

Lombok Island is part of the Sunda-Banda arc system which is one of the most active tectonic regions in the world. In Lombok area there are two subduction zones namely Java trench in the south and Flores back arc thrust in the north. Information on crustal structure is needed to explain the tectonic development and geodynamic interaction of the area. The receiver function is one of the techniques used in the study to identify subsurface and wave velocity structures based on earthquake data regardless of the source mechanism. We analyzed receiver function of teleseismic events (epicenter distance 30-90°) and magnitude more than 6 (M>6) to estimate crustal thickness, Vp/Vs ratio and wave velocity structure beneath KLNI station using H-κ stacking and inversion method. We obtained that the crustal thickness and Vp/Vs ratio beneath KLNI station is about 21.38 km and 2.05. The high Vp/Vs ratio might be an indication of partial melting related to the upwelling of hot asthenosphere material through the subduction slab of Java Trench. The depth of the low velocity zone beneath KLNI station is at 10-18 km which is estimated due to the presence of geothermal