3D modeling of subsurface jiwo fault around gantiwarno sub-district, klaten district, central java using the magnetic method

The Yogyakarta and Klaten earthquake on May 27, 2006, which caused around 5700 people to become victims (from the district of Klaten in 2000 and around 5000 from the Special Region of Yogyakarta). Some earth experts believe that the earthquake was caused by the activities of the Opak Fault in Yogyakarta and the Jiwo Fault in Klaten. That is because the biggest victims are indeed located around the two fault lines. This study aims to map the existence of the Jiwo Fault in Gantiwarno District and surrounding Klaten Regency by magnetic methods. The study area was conducted at an estimated location as the Jiwo Fault with an area of about 20 km x 20 km. Data collecting of total earth magnetic field data in this study using the Proton Precession Magnetometer, while the coordinates of the data collection point are measured with GPS Garmin III Plus. In this study, 150 points were successfully measured. Total magnetic field data is then corrected daily variations and IGRF corrections. The corrected magnetic field data was an inversion of 3D modeling using oasis montaj software. Based on the modeling of the total magnetic field data and the results of the geological survey it was concluded that the dominant geological structure is the fault trending southwest-northeast to west-east, which is interpreted as the Jiwo Fault. Based on the results of 3D modeling using oasis montaj software that began to be seen at a depth of 500 m, it began to be seen clearly at a depth of 1000 m to a depth of 3400 m below sea level is still clearly visible.