MICROEARTHQUAKE FOCAL MECHANISM ANALYSIS IN PATUHA GEOTHERMAL FIELD USING MOMENT TENSOR INVERSION METHOD

• Main Author: Juliani Monica, Laurent
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/63123
• Institution: Institut Teknologi Bandung

The Patuha Geothermal Field is located in West Java and is one of the geothermal fields that has produced 55 MW of energy. Energy production activities in this geothermal field generate micro-earthquakes. The mechanism of the earthquakes is commonly called the focal mechanism, can be estimated by moment tensor inversion. This micro-earthquake focal mechanism will provide information about the triggers for earthquake sources caused by production activities or due to tectonic activities. Research in the micro-earthquake focal mechanism was carried out on seismogram recording data form October 8th – December 10th, 2019, using the moment tensor inversion method. The initial hypocenter location has been determined, but the hypocenters distribution does not form a lineation to the fault. The addition of waveform cross-correlation for the hypocenter relocation determination resulted in two clusters forming a lineation to the faults, one cluster in the West and the other cluster in the East. From the focal mechanism results, the fault parameters for the West cluster are strike N154.47°E, dip 86.25°, and rake 56.6°. For the East cluster, the fault parameters are N326.5°E, dip 79.8°, and rake -0.96°. The earthquake source mechanisms of the opening tensile fault, both in the West and East cluster, occur in the steam zone, which is the vapor reservoir zone, while the earthquake source mechanisms of the closing tensile fault type occur in the liquid fluid area.