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Analysis of Earthquake Risk Estimation for Sustainable Development Using Microtremor Data Based on Vs30 Distribution: Comparative Study of DFA and Geopsy in Central Bengkulu, Indonesia Arya Putra Anggi; Refrizon, Refrizon; Harlianto, Budi; Apriyanti, Nurul; Saputri, Winda; Febriansyah, Gian Ori; Al-Ansory, Andre Rahmat; Raihana, Hana; Daniel, Adrian; Gumanty, Usman
Jurnal Ilmu Fisika Vol 17 No 2 (2025): September 2025
Publisher : Jurusan Fisika FMIPA Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jif.17.2.214-228.2025

Abstract

This research was conducted in Pondok Kelapa Subdistrict, Central Bengkulu Regency, to analyze subsurface characteristics using microtremor data and the Horizontal-to-Vertical Spectral Ratio (HVSR) method. The research compared DFA (Diffuse Field Assumption) and Geopsy approach. In this study, 40 points were measured with a distance between points ranging from 200 to 300 meters. The data were processed using Terraware-HV and Geopsy software with a Monte Carlo approach to model the 3D subsurface structure. Results show that the dominant frequencies range from 0.64 to 8.19 Hz, with high amplification zones between 1.92 and 7.72 concentrated in areas of loose soil, indicating their high seismic susceptibility. Vs30 values range from 55 to 465 m/s, reflecting the dominance of soft to medium materials, such as clay, gravel, sand, and soft rock at specific depths. 3D modeling revealed a heterogeneous distribution of subsurface materials, with high amplification zones requiring special mitigation. This study provides important insights for seismic risk zoning, disaster mitigation, and earthquake-resistant structure design, and supports sustainable development planning in earthquake-prone areas. The results are expected to serve as a reference in spatial management based on earthquake risk mitigation.
Estimate Sediment Thickness in Air Sempiang Village, Kepahiang Using the HVSR Method and the f0 and A0 Values Hafiza, Belliya; S, Vionita; Rabbani, Muhammad Rifqi; Suhendra, Suhendra; Sihombing, Yezra Tariza; Valennita, Valennita; Febriansyah, Gian Ori
Jambura Geoscience Review Vol 8, No 1 (2026): Jambura Geoscience Review (JGEOSREV)
Publisher : Universitas Negeri Gorontalo

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37905/jgeosrev.v8i1.31789

Abstract

Microtremor-based site characterization provides rapid constraints on near-surface stratigraphy where borehole or geotechnical data are limited. This study estimates relative sediment-thickness variation and site response in Air Sempiang Village (Kabawetan District, Kepahiang Regency, Bengkulu Province, Indonesia) using the horizontal-to-vertical spectral ratio (HVSR) method and the derived dominant frequency (f₀) and amplification factor (A₀). Ambient-vibration data were acquired at 13 measurement points (30 min per site) using a PASIGemini-2 three-component geophone. HVSR processing was performed in Geopsy 3.2.2, including time-window selection, spectral smoothing, and peak identification to obtain f₀ and A₀. The resulting parameters were interpolated using inverse distance weighting in ArcGIS to generate spatial distribution maps. The estimated dominant frequencies are predominantly high (approximately 7–20 Hz), indicating generally shallow sediment cover and relatively stiff near-surface conditions, with localized lower-f₀ zones interpreted as thicker sediment accumulations. Amplification factors vary from 2 to 8, with moderate-to-high amplification concentrated in areas inferred to contain softer or thicker sediments, whereas lower A₀ values coincide with zones interpreted as being closer to competent bedrock. The combined f₀–A₀ patterns delineate subareas that are more susceptible to medium- to high-frequency ground-motion amplification and provide a first-order basis for local-scale seismic microzonation and earthquake risk mitigation planning in the study area.