Seismic Tomographic Imaging: Algorithm and Files

List of input and output files

1. PICKS-BISC-1964-2017: Arrival time data the bulletin of International Seismological Center (ISC) for earthquakes that have occurred around the Sumatran Fault System spanning latitudes 10º N - 10º S and longitudes 93º E-114º E.
2. SFILE-06-18: Hand-picked data using SEISAN software. Waveform is obtained from Incorporated Research Institutions for Seismology (IRIS)
3. Global list of seismic stations and their locations (courtesy ISC)
4. A_VMD2: The algorithm used to generated the final model
5. A11-MODEL-DEP-SLICE: Output file for representative depths
6. A11-MODEL-LAT-SLICE: Output file for North-South vertical cross-sections
7. A11-MODEL-LON-SLICE: Output file for East-West vertical cross-sections
8. A11_MODEL-3D: Output file for 3-D model of the study region
9. A_VMD.INC: A common file required by many subroutines in the main algorithm
10. EVENTS: All earthquakes used in the study
11. A13-RESIDUALS: Computed traveltime residuals for all stations and for all events.
12. List of 1-D velocity models. (the iasp91 model is used)

Tomographic results show low-velocity (low-V) anomalies that reflect both accretion and possibly, asthenospheric upwelling associated with subduction of the Australian plate beneath the Eurasian plate around the Sumatra subduction zone (SSZ). The prominent low-V anomaly is thickest around the Conrad, extending beneath Malacca Strait and parts of Peninsular Malaysia, but disappears around the Moho (which appears to be less than 35 km) in the region. Below the Moho, the subducting Australian slab, represented by a high-velocity (high-V) anomaly, trends in the orientation of Sumatra. At these depths, the eastern shorelines of Sumatra, most parts of Malacca Strait and the west coast of Peninsular Malaysia show varying degrees of positive velocity anomalies. We consider that asthenospheric upwelling around the SSZ provide heat source for the 40 or more hot springs distributed North-South in Peninsular Malaysia. Different East-West and North-South cross-sections reveal the subsurface anomalies at various parts of the region. The predominant low-V anomaly is less than 35 km in depth but other low-V anomalies are deeper.