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DELINEATING RESISTIVITY VALUES OF POTENTIAL GEOTHERMAL AREAS ALONG THE BOGOR FAULT USING 2D MAGNETOTELLURIC INVERSION Hardiansa, Debi; Farid, M; Hadi, Arif Ismul; Al-Ansory, Andre Rahmat; Raihana, Hana; Rahmawati, Nurul 'Ilmi
Indonesian Physical Review Vol. 8 No. 2 (2025)
Publisher : Universitas Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/ipr.v8i2.431

Abstract

Kepahiang Regency, located in an active fault zone, has great geothermal potential with an estimated capacity of up to 154 MW(e), making it a strategic renewable energy source to be developed. This research discusses the geothermal potential in the Kabawetan area, Kepahiang, Bengkulu. The main objective of this research is to evaluate the potential of geothermal resources around the Bogor segment by analyzing the subsurface structure using the Magnetotelluric inversion method and 2D resistivity modeling, in order to identify prospective geothermal reservoir zones. It can evaluate the potential of geothermal reservoirs in Kepahiang. The method used is the Magnetotelluric method, which utilizes the Earth's natural electromagnetic field to determine the distribution of resistivity in the subsurface. The results of 2D modeling with the MT method show potential zones associated with variations in subsurface thermal conditions and the presence of conductive clay minerals with resistivity values between 0.14-1 Ωm. These minerals are thought to be associated with the overburden (reservoir) of the geothermal system that has a depth of 2-4 km. The subsurface layer containing hot water and steam originating from heat emitted from the earth's core with a resistivity value of 2.5-45 Ωm at a depth of 1-4 km is thought to be caprock in the geothermal system, a resistivity value of 120-800 Ωm is thought to be hot rock with a depth between 1.5-10 km. It is estimated that there is a type of andesite rock that has been fractured as a reservoir of geothermal fluid. The findings of this research are expected to contribute to renewable energy as an alternative energy in the future, not only for energy needs but also for regional economic development through tourism and to support sustainable governance.
Utilization of Satellite Imagery and Integration of the HVSR Inversion Method for Coastline Changes in the Nangai Beach Tourism Area, North Bengkulu Regency Helinnes, Putri; Hadi, Arif Ismul; Farid, Muchammad; Setyowati, Yuni; Hardiansa, Debi; Gumanty, Usman; Raihana, Hana; Al-Ansory, Andre Rahmat; Muammar, Zaky
Buletin Oseanografi Marina Vol 14, No 3 (2025): Buletin Oseanografi Marina
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/buloma.v14i3.68258

Abstract

This research analyzes shoreline changes in the Nangai Beach area; North Bengkulu Regency using Satellite Image data and analyzes subsurface structures using the Horizontal to Vertical Spectral Ratio (HVSR) method. The main objective of this research is to identify shoreline changes along the Nangai Beach area that occur due to abrasion. Data were collected from 30 points, with a distance of ±100 meters between each point. The research shows that the condition of the area is quite stable to vulnerable to the occurrence of abrasion disasters. Coastline changes were obtained using Satellite Image data from 2011 to 2023. Changes can be observed between points 17 and 35.63 meters, and at point 2, 33.87 meters. The Horizontal-to-Vertical Spectral Ratio (HVSR) method determines dominant frequency values and processes them through amplification to calculate the seismic vulnerability index, sediment layer thickness, and shear wave speed. These values are used to identify areas vulnerable to coastal abrasion. Based on the interpretation, hard rock is shown with a dominant frequency value () in the range 2.35-5.08 Hz, while soft rock is shown in the range 5.71-9.05 Hz. The earthquake vulnerability value () in the range 0.49-2.68 is soft rock, while the value range 3.42-5.61 is hard rock. The lower the vulnerability value (), the more susceptible the area is to abrasion. The shear wave velocity () value is low with a range of 186.83-350.85 while the high value is with a range of 350.85-596.87. A layer of rock with a 3D cross-section can be viewed using 3D modeling software by entering the value of Vs. This research makes a significant contribution to abrasion disaster mitigation through a geophysical approach.
Seismic Site Response Characterisation of Sungai Serut Sub-district, Bengkulu City, Using the Horizontal to Vertical Spectral Ratio (HVSR) Method Rendoza; Farid, Muchammad; Refrizon, Refrizon; Hardiansa, Debi; Al Ansory, Andre Rahmat; Raihana, Hana
Jurnal Fisika Unand Vol 15 No 2 (2026)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.15.2.204-210.2026

Abstract

Bengkulu City, located on the west coast of Sumatra, is highly susceptible to seismic hazards due to active tectonic settings. This study investigates subsurface characteristics, ground amplification, and the seismic vulnerability index (Kg) in Sungai Serut Village using the Horizontal to Vertical Spectral Ratio (HVSR) method based on microtremor measurements. The results indicate that the dominant frequency (f₀) ranges from 1.00 to 6.87 Hz, reflecting variations in sediment stiffness and near surface geological conditions. Based on the dominant frequency distribution, the subsurface materials are predominantly classified as type II soil, which generally corresponds to medium-density sedimentary deposits. The spectral amplification factor (A₀) varies between 1.64 and 5.88, indicating moderate to high amplification levels. The seismic vulnerability index (Kg) ranges from 0.51 to 20.49, with the highest values observed at measurement points 20 and 21, suggesting greater susceptibility to strong ground motion. These findings provide important insights for seismic hazard assessment and support earthquake-resilient spatial planning and infrastructure development in Bengkulu City.