Investigation of crustal structure in Nias Island, Sumatra using P-wave receiver function analysis

Abstract

In this study, we invert the receiver function beneath GSI seismic station to estimate the crustal structure beneath Nias Island, Sumatra. The receiver function is computed from 24 teleseismic events using a time-domain deconvolution technique and divided into three groups by observations with similar back azimuth namely GSI_NW, GSI_NE, and GSI_SE. The resulted receiver function then stacked to increase the signal-to-noise ratio. The shear wave velocity structures of the crust are obtained by inverting receiver functions using linearized-iterative inversion with A0K-135 for the initial model. The inversion result shows a thick sediment layer ranged from 1 to 3 km with velocities around 2,4 km/s near the surface. The Moho and the top of the subducting oceanic slab are observed around 22-24 km and 32 km depth respectively. The low shear wave velocity above the transition to the subducting slab is suggested as the signature of the serpentinization.