Mikrozonasi Kerentanan Seismik Berbasis Metode HVSR di Kapanewon Prambanan, Kabupaten Sleman

Seismic Vulnerability Microzonation Based on the HVSR Method in Kapanewon Prambanan, Sleman Regency

Abstract

Kapanewon Prambanan, Sleman Regency, is situated within the Yogyakarta Basin, characterized by complex geological conditions and thick sedimentary layers that can significantly amplify seismic ground motion. During the 2006 Yogyakarta Earthquake, this area experienced severe damage with an intensity reaching VII on the Modified Mercalli Intensity (MMI) scale. Therefore, seismic vulnerability microzonation is crucial in supporting effective earthquake mitigation strategies. This study aims to map the seismic vulnerability index in Kapanewon Prambanan using the Horizontal-to-Vertical Spectral Ratio (HVSR) method based on microtremor measurements. The HVSR method was applied to obtain the dominant frequency, amplification factor, and seismic vulnerability index. Furthermore, inversion of the H/V curves was performed to estimate the shear-wave velocity profile, particularly the Vs30 parameter. The results indicate that the dominant frequencies range from 0.98 to 17.13 Hz, amplification factors range from 1.06 to 11.69, Vs30 values range from 114 to 726 m/s, and seismic vulnerability index values range from 0.18 to 7.46. Areas with low seismic vulnerability are generally associated with the Semilir and Kebobutak Formations, while moderate to high vulnerability zones are predominantly distributed within the deposits of the Young Merapi Formation. The resulting seismic microzonation map is expected to serve as a valuable reference for spatial planning, infrastructure development, and earthquake risk mitigation in the Prambanan area.