Soil Vulnerability Analysis Using the Microtremor Method for Mapping the Landslide Susceptibility Area in Batu City, Indonesia

Based on Regional Agency for Disaster Management (BPBD) Batu City data, Indonesia, 36 landslides have been recorded in the last three years around the Payung area, where this area connects several regions around Batu City. So, it is necessary to map areas with potential ground movement as an initial step for the local government in formulating a landslide disaster management strategy. This research aims to map landslide susceptibility areas around Payung, Batu City, identified based on the soil vulnerability index value range in the peak ground acceleration (PGA) mapping results. The data was measured using the microtremor method. There were 22 measurement points in 3 zones with different heights, and the microtremor signal was recorded for 35-40 minutes at each point. The microtremor signal from seismic recording is composed of three components (NS, EW, and Up-Down), which are used to develop the Horizontal to Vertical Spectral Ratio (HVSR) technique, where the ratio value is obtained by comparing horizontal (H) components (H_NS and H_EW) to the vertical component (Up-Down (V)). The research results show that landslide susceptibility areas are located at points M10, M13, and M16, with a soil vulnerability index range of 21-40.1. When a landslide occurs in that area with high vulnerability, it will impact points along Payung Street at points M3–M9. The points with high soil vulnerability index values need special treatment to reduce the impact of landslides.