Depth estimation of Moho discontinuity beneath Central Indonesia by the cross-correlation analysis of seismic ambient noise
Abstract
Central Indonesia has complex tectonic structures which is characterized by several subduction zones at northern and eastern part and active faults (e.g., Palu Koro, Matano and Hamilton faults). Our previous study at Central Indonesia (Budiati et al., JpGU, 2018) found the clear discrepancy between observed group velocities and synthetics by CRUST 1.0 (Laske et al., 2013) at period of 25s - 30s. Based on that, this study aims to assess the Moho discontinuity by comparing observed Rayleigh wave group velocities obtained from ambient seismic noise cross-correlations and synthetic group velocities by adjusted CRUST 1.0 at longer periods which are more sensitive to deeper layers. We collected 5 months continuous waveform data from vertical components of 10 broadband stations around Central Indonesia. Firstly, the continuous data were divided into 20 minutes segments with time shift in every 5 minutes. Once the pre-processing steps for each segment were done, we calculated the CCFs between two contemporaneous segments from two stations and stacked the daily-averaged CCFs over 5 months. We further compressed the two-sided signal into one-sided signal by taking the average of positive and negative lag part of the CCFs in order to stabilize the dispersion curves of group velocities. However, for several stations pairs the group velocities at 2-sided CCFs are more stable than at 1-sided CCFs. To fit the synthetic and the observed group velocities, we simply changed the crustal thickness. By the visual inspection of comparison of the observed and synthetic group velocities at period of 25s - 30s, we find the best depth of Moho discontinuity at the depth range of 30km - 45km. We estimated the depth of Moho at 10 station pairs and grouped the estimated depth of Moho discontinuity into two groups: at 30km - 34km for eastern part of Central Indonesia which is related to ocean crust, Batui and Sula thrust and 35km - 40km for continent of Sulawesi Island.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T23A0345K
- Keywords:
-
- 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8107 Continental neotectonics;
- TECTONOPHYSICSDE: 8175 Tectonics and landscape evolution;
- TECTONOPHYSICSDE: 8177 Tectonics and climatic interactions;
- TECTONOPHYSICS