Identification of Moho Discontinuity Depth and Subduction Slab in Bengkulu and South Sumatra Region using Receiver Function Method: A Preliminary Result

Abstract

Bengkulu and South Sumatra regions are areas with high seismic activity due to faults and subduction zones. This study aims to analyze the depth of the Moho discontinuity layer and subduction slab under 4 BMKG seismic stations that form a perpendicular line of trench in the Bengkulu and South Sumatra areas. The distribution of stations used are Enggano Station (EGSI) in the front arc islands, Manna Station (MNAI) in the front arc basin, Pagar Alam Station (PKSI) in the volcanic-arc zone, and Lahat Station (LHSI) in the proto-volcanic zone. We selected teleseismic earthquake data with a distance of 30°-90° from the stations and magnitudes above 6 (M>6). For the identification of Moho and slab depths, we used analysis of receiver functions with iterative time domain deconvolution and migration of receiver functions with the AK-135 velocity model. The Oceanic Moho layer and the subduction slab under the EGSI Station were identified at depths of 34 km and 23 km respectively, under the MNAI Station the Moho layer and the subduction slab were identified at a depth of 18 km and 87 km respectively, under the PKSI Station the Moho layer and the subduction slab were identified at a depth of 34 km and 129 km respectively, and under the LHSI Station the Moho layer and subduction slab were identified at depths of 35 km and 175 km respectively.