ANALYSIS OF RELOCATION OF AFTERSHOCK EARTHQUAKE HYPOSENTER YOGYAKARTA DATED 11-14 JUNE 2006 USING DOUBLE DIFFERENCE METHOD AND CALCULATION OF LOCAL MAGNITUDE

• Main Author: Putra Pratama, Randi
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/46803
• Institution: Institut Teknologi Bandung

On May 27 2006, an earthquake occured in Yogyakarta and its surroundings, including the districts of Bantul, Klaten, Gunung Kidul and Kulon Progo. The USGS recorded the earthquake occurred at 05:53:58 WIB with the position of the epicenter 7.97º South Latitude and 110.44º East Longitude, depth of 10 km, and moment magnitude 6.3 MW. The earthquake on May 27, 2006, showed an unknown fault in about 10-20 km east of the Opak fault. Whereas in another study stated that the main cause of the earthquake was the synistral fault within 5- 10 km to the east of the Opak Fault. Due to differences in the results of the study, it is necessary to relocate using the Double Difference method using the aftershock earthquake waveform data in Yogyakarta on June 11-14, 2006. The initial phase begins with picking the P and S wave arrival time using the Seismic Analysis Code software, determining the initial hypocenter used Hypoellips software, determination of event pairs using ph2dt, hypocenter relocation using HypoDD software and determination of local magnitude. The results of the initial hypocenter determination using hypoellips showed two clusters, in which the main cluster had a lineage distribution of the aftershock earthquake epicenter in the east which traced southwest - northeast. The results of relocation using a combination of cross correlation data and catalog data show more dense results and produce three more convergent clusters with firmer lines. The main cluster forms a fault line trending southwest northeast with a orientation of 45° NE dip 82° S and has a distance of 10 KM east of the Opak fault. In addition, between kalster 1 and clister 2 form the Graben system. There is a decrease in the trend of local magnitude values over time