APPLICATION OF DOUBLE-DIFFERENCE TOMOGRAPHY AT GUNTUR VOLCANO, GARUT

• Main Author: RISALDI (nim : 12405010), INDRAPRASTA
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/22576
• Institution: Institut Teknologi Bandung

In this seismic tomography study, we used Double-Difference Tomografi (TomoDD) method (Zhang and Thurber, 2003) to invert for seismic velocities structures beneath Guntur volcano that is located in Garut, West Java, Indonesia. This method simultaneously determine seismic velocities and hypocenter improvements. TomoDD method uses a combination of absolute and more accurate differential arrival times data. This method is also able to produce more accurate event relocations and velocity structure near the source region. The TomoDD inversion results show the negative P-wave velocity anomalies are located beneath the summit of Guntur Volcano, which may be associated with hot materials or high fluid contents. Meanwhile, the S-wave velocity structure models show positive velocity anomalies beneath the summit of Guntur volcano. Generally, the S-wave tomograms show that the S-wave travel faster than the P-wave it means that Vp value is low while Vs value is high. This phenomenon may be caused by poor accuracy of the S-wave arrival time pick. Therefore, the Vp/Vs tomograms are difficult to interpret due to existing of the fluid materials beneath the Guntur volcano. Relocated hypocenter using TomoDD code shows quite satisfied result where relocated hypocenters seem to be more focus and forming straight pattern from Gandapura caldera to Guntur summit, and they also seem focus on 4 - 6 km depth below Guntur summit that is consistent with previous geological study by Alzwar et al, 1992.