Retrieval of the Pwave reflectivity response from autocorrelation of seismic noise: Jakarta Basin, Indonesia

We autocorrelate the continuously recorded seismic wavefield across a dense network of seismometers to map the Pwave reflectivity response of the Jakarta Basin, Indonesia. The proximity of this mega city to known active faults and the subduction of the Australian plate, especially when the predominance of masonry construction and thick sedimentary basin fill are considered, suggests that it is a hot spot for seismic risk. In order to understand the type of ground motion that earthquakes might cause in the basin, it is essential to obtain reliable information on its seismic velocity structure. The body wave reflections are sensitive to the sharp velocity contrasts, which makes them useful in seismic imaging. Results show autocorrelograms at different seismic stations with reflected-wave travel time variations, which reflect the variation in basement depth across the thick sedimentary basin. We also confirm the validity of the observed autocorrelation waveforms by conducting a 2-D full waveform modeling.