Identification of ground motion prone areas triggering earthquakes based on microtremor data in Jati Agung district, South Lampung Regency, Lampung, Indonesia

Abstract

Jati Agung District is an area planned by the Lampung government to become a new city of the central government in Lampung. Aspects of city planning include aesthetics and safety. The geophysical study is conducted as disaster mitigation efforts to make the city have a good level of safety. The purpose of this study is to measure earthquake activities in the research areas that could be developed as data in disaster mitigation. The geophysical study was conducted by measuring the microtremor at 15 points. The microtremor signal is processed by the HVSR method to obtain information on natural frequency and amplitude. Natural frequencies and amplifications were analyzed to obtain the Peak Ground Acceleration (PGA) and Ground Shear Strain (γ) values. The results of PGA values and Ground Shear Strains indicate indications of soil fracture-prone areas. The results showed that the PGA value was 12.34638 gal to 22.18974 gal, while the Ground Shear Strain (γ) value was 53.34322x10-6 to 729.6847x10-6. The area of this study is a very safe area against the impact of earthquakes. Because the deformation in the event of an earthquake is very small, this is due to the type of rock found. In the study area, the type is rock that has large compacting properties. Also based on the geography on this research area is a region that is quite safe from tsunami waves, because in the west there are high mountains, and there are also small islands that can reduce tsunami waves from the southwest of the research location (Jati Agung Area).