DefinePK

Abstract

The earthquake that occurred in Yogyakarta and surrounding areas on May 27, 2006 killed thousands of people and caused a lot of damage. The earthquake was caused by an activated of the Opak Fault and the Dengkeng Fault. Previous research on Dengkeng Faults has not been well publicized. The Dengkeng Fault in the research area is in the northeast of the Opak Fault, which is located in the sub district of Gantiwarno and surrounding in Klaten district. The existence of the Dengkeng Fault can be identified using geophysical methods, one of which is the gravity method. Gravity data used in this study are primary data with a distribution point of 94 field measurements with semi grid distribution. Data that has been obtained in the field needs to be corrected so that it becomes a complete bouguer anomaly data. Complete bouguer anomalies are then separated using upward continuation to obtain regional anomalies and local anomalies. The local anomaly is then analyzed using gradient analysis in the form of first horizontal derivative and second vertical derivative to determine the contact boundary position and direction of the fault. The depth of the fault can be estimated using Euler deconvolution analysis. In this study, the results of the gradient analysis in the form of first horizontal derivatives and second vertical derivatives show that the fault is in the UTM coordinates of zone 49 S from 444500 meters and 9141000 meters to 456250 meters and 9139000 meters in the west to east direction. Modeling with Euler deconvolution analysis shows that the estimated depth of the fault is between ± 400 meters to ± 800 meters.