Identification of soil characteristics in the Central Java Region using the HVSR (Horizontal to Vertical Spectral Ratio) inversion method

Abstract

This research aims as one of the efforts to mitigate earthquake disasters by using the HVSR method based on microtremor data at 28 BMKG seismic stations in the central Java Island region to estimate the dominant frequency (f0) and amplification (A0) that describe the dynamic characteristics of the soil and analyse the shear wave velocity at a depth of 30 meters (Vs30). The dominant frequency values in the study area range from 0.648 to 18.257 Hz. The amplification values scattered in the study area ranged from 0.788 - 7.496. This research also produces dominant period parameters (T0) and seismic vulnerability (Kg). The highest seismic vulnerability values are at BUJI in Buayan, Kebumen; GBJI in Gringsing, Batang; and SBJM in Sanden, Bantul. In addition, the Vs30 value is helpful to determine how strong the building foundation resists earthquakes. Based on the Vs value in the ground profile with ellipticity curve modelling, the Vs30 value ranges from 204.756 - 903.046 m/s. The distribution of Vs30 values shows that the research points in central Java are spread by a variety of hard and very dense soil types to soft rock (SC).