ESTIMASI KEDALAMAN SESAR KERINCI MENGGUNAKAN METODA MAGNETIK

Abstract

The Kerinci fault is one segment that always interesting to be examined. The results of previous studies showed that Sungaipenuh and surrounding area are located above an active fault. Fault mechanisms are believed to cause the onset of earthquakes in the area in the past. How the fault system formed is strongly influenced by the pattern geometry and properties of rock magnetism. This study aims to identify and estimate the depth of fault in Kerinci segment using magnetic methods. Magnetic surveys trending from west to east in Kerinci segment held on 10 to October 20, 1995, a few days after the earthquake. There are two tools in research, these are G-856 magnetometer and a GPS. Magnetic anomaly data are transformed into the wave number domain using Fourier transforms. Fault depth is estimated based on the slope of the power spectrum of magnetic anomalies. Fault geometry is modeled using a 2D prism and the estimated depth is the depth of the center, top and bottom of the prism. The results showed that the magnetic method can not identify the presence of faults in the eastern town of Sungaipenuh, but can identify the existence of faults in the area west of the city Sungaipenuh. An estimated depth of the center section, top and bottom is 0.812 km, 1.633 km and 2.454 km respectively. These results are consistent with the results of the gravity method.

Keyword : Magnetic anomaly, Fourier transform, power spectrum, the 2-D prism, depth of fault, the Fault Kerinci.