Seismic Velocity Structures in the Western part of Java from Body-Wave and Ambient Noise Tomography

Abstract:

We reconstructed a 3D seismic velocity model beneath the western part of Java using body-wave and ambient noise tomography. We applied double-difference tomography to P and S wave arrival data from ~1000 events to obtain an upper mantle velocity model and ambient noise tomography from ~75 temporal stations to obtain a crustal velocity model. The combination of both methods can lead to a better understanding of the velocity structure beneath the study area. The body wave tomography provides a clear image of features beneath the volcanic arc, including a zone that may reflect the presence of partial melt. We applied the trans-dimensional tree method to generate Rayleigh wave group velocity maps. We observed a contrast from low to the high velocity of the shallow crust in the Northwest-Southeast direction, which has good spatial correspondence with maps of surface geology. The velocity model obtained from this study could be used to obtain better-constrained earthquake locations, which will contribute to disaster risk mitigation efforts by better characterization of earthquake sources in the western part of Java.