IDENTIFICATION OF THE DEEP CRUSTAL STRUCTURES ON THE MIDDLE AND SOUTH SUMATRA AREAS USE AMBIENT NOISE TOMOGRAPHY

• Main Author: DESTAWAN - Nim: 22316011, RIDHO
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30445
• Institution: Institut Teknologi Bandung

<p align="justify">The island of Sumatra has a complex structure and tectonic order. Located in a subduction zone makes it an area that has a ranks of volcanoes along Sumatra active fault that cuts across the island's entire body. These conditions make the island of Sumatra and surrounding areas as one region with high seismisitas. In this study, ambient noise seismic interferometry studies were conducted to obtain the empirical Green's function (EGF) from surface waves (Rayleigh waves). 3D subsurface model of shear velocity structure (Vs) obatained by ambient noise tomography (ANT). EGF was obtained by cross-correlation of 40 BMKG observation point stations with recording range between April and December 2015. The results of data processing show that the dispersive signal is clearly visible on the gather data with period of 5 - 40 s, group velocity between 2.8 - 3.0 km/s and average phase velocity between 3.0 - 4.5 km/s. Based on the results of ANT at a depth of less than 30 km high velocity anomaly pattern along the Sumatra Fault zone and the Bukit Barisan Volcano ranks are interpreted by the remaining material of magma. While the area of the back-arc basin is dominated by medium to low anomaly that are interpreted as sediment units. At a depth of more than 30 km, low anomaly contrast along the Sumatra Fault zone indicated as the existence of a mantle diapir. <br /> <br /> Keywords: Interferometry, empirical Green’s function (EGF), ambient noise tomography (ANT), velocity anomaly, Sumatra Island. <p align="justify">