Updating S-velocity profile around Cimandiri fault zone derived from inversion of receiver functions: New constraint from parameters of complex structure

Abstract

In this study we update the S wave velocity model near the Cimandiri fault zone obtained from the inversion of teleseismic receiver function by incorporating the contribution of complex structure. The research area is situated near the fault zone in which the calculation of receiver functions is heavily affected by the presence of the fault providing backazimuthal variation in the amplitude of receiver functions. In this situation the traditional inversion method may not provide satisfied models. Thus, in this study we employ Neighbourhood Algorithm method with an initial model containing the properties of shallow dipping fault and anisotropic mantle subducted slab in the inversion process. To speed the computation process, we use the crustal properties obtained from the previous studies and only make variation in the near surface layers (sediment and basement layers) and upper mantle properties. The inversion result shows very good fitting between our actual data and synthetic receiver functions. The result suggests that the orientation of dipping structure beneath the station is well resolved. The best velocity model reveals that the shallow dipping feature related to the fault is striking N74°E and dipping -30°. The structure properties obtained from our best model is consistent with the Cimandiri fault model resulted from other geological and geophysical studies.