Identification of Capable Fault Location around Mount Betung Area Based on GPS Strain Data

Abstract

Abstract Sumatran Island is located in a very active tectonic zone due to subduction of Indian-Australian plate beneath Eurasian plate. This causes an increase in stress in the subduction zone thereby increasing the pressure and strain. Mount Betung, which is situated in Sumatra Island, is located in the province of Lampung with a developing economy in recent years. Therefore, understanding the strain related to earthquake hazard is important to be conducted. The strain is a tool to help in identifying capable fault location in the geodetic aspect. The purpose of this study is to identify capable fault location to ensure the safety of development and construction around Mount Betung. GPS velocity data from 2006 to 2019 on seven sites are used as tool to calculate the strain which is used to identify the capable fault. GPS strain is calculated on the every triangles and polygons possible formed by the combination of three sites or more. There are two cases for identification, and triangles or polygons within each case do not intersect each other. The capable fault is identified in the area with the strain value of more than the threshold which is determined in the area of Sumatran Fault Zone. The threshold value resulted from the studies is 0.47 microstrain/year. The velocities of sites are ranging from -2.48 to -0.02 cm/year. The area with capable fault is identified around the Sumatran Fault Zone or the extension of the fault. The area close to the capital of Lampung Province, Bandar Lampung is relatively safe since there is no identified capable fault.