Analysis of Horizontal to Vertical Spectral Ratio (HVSR) Microtremors in Quaternary Sediment Area, Takalar Regency, South Sulawesi Indonesia

Abstract West coast area of Takalar district is the central government area which is experiencing significant population growth and infrastructure development. The research area is located above alluvium deposit and has natural hazard potential triggered by Walanae Fault, Selayar Fault and Flores Back Arc Thrust Fault, which are the main seismic sources close to research site. Seismic disasters can be caused by several factors including distance, earthquake strength and local site effects. In this research, the authors used Horizontal to Vertical Spectral Ratio (HVSR) microtremor method, by comparing the horizontal to vertical components to obtain shallow factors to describe the local characteristics of research site. Takalar microzonation aims to map areas based on seismic vulnerability in the Quaternary Sediment site in Takalar Regency. The research results show that local conditions of the research site are dominated by soft to very soft soil. Coastal areas have softer characteristics and harder away from the coast. The results of microtremor microzonation show that coastal areas have low dominant frequency. This indicates that the sediment thickness is thicker, make those areas vulnerable to seismic shocks. Meanwhile, the seismic vulnerability index results are dominated by the high category throughout the research site and the amplification factor values are low to high. The authors hope this research can be used as a consideration for relevant stakeholders to mitigate potential of seismic disaster hazards in Takalar Regency.