DETERMINATION OF AFTERSHOCK HYPOCENTER LOCATION AND 3-D SEISMIC VELOCITY STRUCTURE AROUND THE SOURCE OF MAY 27, 2006 Mw 6.4 YOGYAKARTA EARTHQUAKE

• Main Author: MI’ROJUL HUSNI (NIM: 22315004), YAYAN
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/24766
• Institution: Institut Teknologi Bandung

The Special Region of Yogyakarta experience a fairly high seismic activity due to its location in an active tectonic setting. One of the active fault in this region is the Opak fault which striking south west - north east. In this study, we analyzed aftershocks sequence through waveform data which taken from 16 temporary GeoForschungsZentrum (GFZ) network stasiuns located around the Opak Fault. We selected the event from the waveform which have (time difference between S-and P-wave arrival time) ts-tp< 7 second, and have picked carefully manually by eye the arival times of the aftershock in the period of 3 June to 6 June 2006. For determining the aftershock hypocenter location, we used the non-linear algorithm from NonLinLoc program. The results of aftershock hypocenter determination with non-linear method then becomes input for tomography inversion porcess using LOTOS 12 program. The results of the tomography inversion process gives a clear velocity structure beneath Opak fault area. The contrast of velocity anomaly from the vertical section of tomogram indicate the stucture of the fault, and the high value of Vp/Vs which is 1.8 – 1.81 under the Opak fault could indicate the properties of the petrophysical.