STUDY OF SEISMIC TOMOGRAPHY OF PAPANDAYAN VOLCANO : Abstract

• Main Author: <br> NIM. 224 02 011, Kristianto
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/6366
• Institution: Institut Teknologi Bandung

</i><b>Abstract: <i></b><p align="justify"> Within June - July 1998 volcanic earthquakes of Papandayan Volcano increased. The average of volcanic earthquakes recorded was 4 events a day. During the period 7 digital earthquake recorder stations were installed around the volcano. Location of hypocenter of 60 volcanic earthquake events can be determined using Geiger method. Initial velocity 1-D model was determined by travel time curve (Telford., et al 1977). The minimum travel time from a source of earthquake to a receiver was calculated by ray tracing with a pseudo-bending method. The block element was choosen to be 2 x 2 x 2 km<sup3</sup> based on distribution of earthquake receiver station and hypocenter.<p align="justify"> Input for seismic data inversion process is travel time difference between seismic wave in the earth (t_obs) and seismic wave in the reference velocity model (t_cal). While inverse problem uses approach of linear (Ax=dt) with LSQR method, with two damping type application; there are explicit and implicit damping. The explicit damping consists of minimum norm and gradient damping.<p align="justify"> Seismic tomography of Papandayan volcano gives a negative velocity anomaly structure 6-10 km depth from the reference below Walirang volcano or 4.6-8.6 km depth from Papandayan summit. The location is related to hot area. This result is supported by earthquake spectrum at 8-10 km in depth that indicates attenuation pattern when the seismic wave was passing negative velocity anomaly area.</p>