Identification of Active Fault Traces O “Paleo Earthquakes” Using Gravity Methods in Jangkat, Merangin Regency

Abstract

Background: Indonesia is a country with high seismic activity because it is located at the meeting point of four major tectonic plates, resulting in numerous active faults and susceptibility to geological disasters such as earthquakes and landslides. Despite the high risk, data on active faults and geological disasters in Indonesia is still limited. This study focuses on geological mapping to identify Active Fault Traces, specifically “Paleo Earthquakes,” in Jangkat District, Jambi Province. Objective: The purpose of this study is to update and verify the position of faults from old geological maps, as well as to interpret new deformation mechanisms resulting from the interaction of geological structures in the field. Methods: Through preliminary studies and analysis of field data, as well as secondary geophysical data. Based on the results of geological structure measurements in the field, there are three fault locations consisting of a left-lateral strike-slip fault, a right-lateral strike-slip fault, and a right-lateral strike-slip fault. Results: Analysis of the residual map shows residual gravity anomalies with amplitudes of -9.6 to +11.0 mGal. The dominance of positive anomalies in the southwest is interpreted as an active fault and is significantly consistent with the distribution of active faults identified in the field. Conclusion: A linear residual anomaly pattern with a relatively high northwest- southeast gradient that correlates directly with the fault segment can be seen on the alignment map, which shows the general direction pattern. The results of the research location analysis are traces of active faults from paleo-earthquakes that have been identified through field and gravity data.