IMAGING OF SUB-SURFACE STRUCTURE BENEATH 2015-2017 JAILOLO, HALMAHERA EARTHQUAKE SWARM ZONE USING AMBIENT NOISE TOMOGRAPHY

• Main Author: Nur Vita, Aprilia
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/68159
• Institution: Institut Teknologi Bandung

Earthquake swarm sequence activities occurred in Jailolo, Halmahera at the end of 2015 until 2017 within volcanic complex of Jailolo volcano. These rise of swarm activities often signals volcanic unrest. The swarm assumed have been triggered by laterally migrating dike. Therefore, investigation of structure and magmatic or non-magmatic fluids existence in the uppermost crust is important to understand earthquake generation in volcanic area. Identification of existence of fluid or structure in Jailolo subsurface is able to understand through tomographic imaging. The image of subsurface structure or fluid existence are represented by seismic wave velocity associated with characteristic of subsurface material. We will present shear velocity model around Jailolo volcanic complex, basen on ambient noise tomography applied to data from 35 temporary station of 7G BMKG-GFZ seismik network that deployed after swarm earthquake activity escalated in Jailolo. Anomaly of Vs structure appeared as high velocity zone (>20% perturbation) beneath Jailolo Volcanic Complex and Jailolo Bay. While the appearance of low velocity zone (<-20% perturbation) in the shallow depth can be associated with pyroclastic deposits and hydrothermal system