3-D shallow shear velocity structure of the Jakarta Basin from transdimensional ambient noise tomography.

ABSTRACT: Situated on the northern coast of the Indonesian island of Java, Jakarta and its metropolitan area (Greater Jakarta) are subject to significant earthquake hazards from a subduction zone south of Java and nearby active crustal faults. The seismic risk may be even higher because Greater Jakarta resides on a sedimentary basin filled with thick Pliocene-Pleistocene sediments. A comprehensive study of Jakarta Basin's properties and geometry is important for creating robust seismic hazard and risk assessments. The main objective of this study is to develop a 3-D model of Jakarta Basin's shallow shear-wave velocity (V_S ) structure and improve on previous models that did not cover the basin edge due to the extent of data coverage. Between April and October 2018, we deployed a new temporary seismic network to extend the spatial coverage beyond that of a previous deployment in 2013, and sampled 143 locations through sequential deployments of 30 broad-band sensors covering Jakarta and its adjacent areas. We conducted a 2-stage transdimensional Bayesian inversion of Rayleigh wave phase velocity dispersion curves derived from seismic noise. To begin, we applied tomography and constructed 2-D phase velocity maps for periods 1-5 s. Then, at each point in a regular grid defined on these maps, we invert each dispersion curve into 1-D depth profiles of V_S . Finally, these profiles at gridpoints with ∼2 km spacing are interpolated to form a pseudo-3-D V_S model. Our results reveal the edge of the Pliocene-Pleistocene sediments along the south. Also, we resolve a basement offset across south Jakarta that we suggest may be related to the western extension of the Baribis Fault (alternatively, the West Java Backarc Thrust). We recommend using this 3-D model of the Jakarta Basin for scenario earthquake ground motion simulations. Such simulations would help establish how important it might be to re-assess seismic hazard and risk in Greater Jakarta so that basin resonance and amplification are considered.

SUBMITTER: Ry RV 

PROVIDER: S-EPMC10173864 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature