Re-modeling kaligarang fault base on satellite gravity data

Abstract

The Kaligarang River heading North-South divides the region of Semarang. The Dutch Colonial Government recorded the territory of Semarang on January 19, 1856, shaken by an earthquake on the mainland epicenter with the strength of the V-VI MMI. Fault Kaligarang has a sliding rate of slip (slip rate) of 4.5 mm per year. The value of rock slip rate is relatively very small, but if accumulated over a long period, its value can increase and it will form an earthquake when energy is released. Kaligarang fault is still active and can cause another earthquake. Estimates of active Kaligarang fault are analyzed using different analytical methods by combining 3 methods (magnetic, gravity, and geological). Preliminary studies were conducted using the gravity method used satellite data. The purpose of this study was to determine the ability of satellite data to be used as supporting data for preliminary research and also as complementary data. There are similarities in the results of inversion modeling with using GgmPlus data and geological data in the field. This result cannot prove the kaligarang fault because kaligarang fault is a transform fault. The distribution of subsurface mass can prove the existence of faults in the Semarang area but not at all, so that terrestrial data are still needed to obtain a more complete subsurface geological structure. Others method are needed to complete and prove the Kaligarang fault is active.