Imaging the Velocity Structure of Rayleigh Wave in Sulawesi Island Using Ambient Noise Tomography

Abstract

Ambient Noise Tomography (ANT) had been applied to describe the Rayleigh wave group velocity model in the crust part of
Sulawesi Island. The research data were vertical component waveform data from July 2016 to December 2017 of 25 INA TEWS
BMKG network seismograph in Sulawesi Island. In general, the steps of conducting research are divided into several parts,
namely single data preparation, crosscorrelation and stacking, cross-correlogram analysis, measurement of dispersion curves,
velocity tomography and the last is the interpretation of research results. The estimated travel time of the Rayleigh wave group for both 5 s and 12 s periods was obtained from the time delay of the cross-correlation result. The tomography process was conducted by using FMST v1.1 where forward and inverse modeling was performed iteratively. The modeling result for the period
5 s showed that the distribution of negative anomalies corresponded to volcanoes and Inter-Volcano plains which were Quarterold. For the period 12 s, the east arm of Sulawesi Island had a lower velocity anomaly than around other regions on the Sulawesi Island. This indicated that the tectonic activity and geological condition of Sulawesi Island was complex.