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Analisa Lapisan Sedimen Bawah Permukaan Pada Pembangunan Jalan Elevated Danau Dendam Tak Sudah Kota Bengkulu Menggunakan Metode HVInv Setyowati, Yuni; Farid, Muchammad; Ismul Hadi, Arif; Helinnes, Putri; Hardiansyah, Debi; Refrizon, Refrizon; Gumanty, Usman; Raihana, Hana; Rahmat Al-Ansory, Andre; Taufiqurrahman Syah, Muhammad
Jurnal Ilmu Fisika Vol 16 No 2 (2024): September 2024
Publisher : Jurusan Fisika FMIPA Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jif.16.2.187-197.2024

Bengkulu City is situated within a subduction zone where the Indo-Australian and Eurasian tectonic plates converge, rendering the area highly susceptible to seismic activity. This study employs the microseismic method to assess seismic vulnerability and the subsurface rock structure at the Dendam Tak Sudah Lake Flyover Construction Site in Bengkulu City, which encompasses a swampy region. The microseismic method used was an inversion of the horizontal to vertical (H/V) spectral ratio (HV-Inv) for determining the dominant frequency (f0), amplification factor (A0), seismic sensitivity index (Kg), and shear wave velocity (Vs). The findings reveal that f0 in the study area range from 2.16 to 7.53 Hz, A0 vary from 0.40 to 3.79, and Kg values span from 0.03 to 6.04. The sedimentary layers exhibit an average thickness of 5-10 meters, with some locations showing significantly thicker sedimentary deposits. Notably, the highest seismic susceptibility is recorded at point T8. The Vs values range from 185.19 to 539.49 m/s, which are inversely proportional to the Kg values and indicate soil classifications varying from soft to medium. The overall seismic risk in the study area is moderate. These results offer key insights into geophysical and geological conditions in Bengkulu City, crucial for earthquake mitigation.

Estimation of Geothermal Potential Area in Kabawetan Sub-District, Using 2D Magnetotelluric Inversion Method Gumanty, Usman; Farid*, Muchammad; Refrizon, Refrizon; Azzahra, Gusti Ayu Zahwa; Nurhayati, Ratna Dewi; Al Ansory, Andre Rahmat; Raihana, Hana
Aceh International Journal of Science and Technology Vol 14, No 1 (2025): April 2025
Publisher : Graduate School of Universitas Syiah Kuala

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13170/aijst.14.1.44628

Kabawetan is located in the subduction zone of the magmatic arc in the Indonesian tectonic system. The geothermal energy potential in this region is closely tied to volcanic activity, which is prevalent along the Ring of Fire on the island of Sumatra. This study aims to identify the distribution of subsurface resistivity values related to geothermal potential in the Kabawetan Region. To achieve this, the magnetotelluric (MT) method is used, utilizing electrical and magnetic sensors. Data were collected using two horizontal electrical sensors (Ex, Ey) and three magnetic sensors, including two horizontal sensors (Hx, Hy) and one vertical sensor (Hz). Measurements using the magnetotelluric method can be used to determine the subsurface rock layers based on resistivity values. The results of data processing yield a 2D cross-section of the resistivity value, which characterizes the potential for geothermal energy. This study used four measurement points to analyze resistivity variations and determine geothermal potential. Field measurement data were processed using MAPROS software, and a 2D cross-section model was created using ZONDMT2D. The results showed that resistivity values of 20-60 m, thought to be impermeable overburden, were at depths of 0-1.5 km and 2.5-4 km, resistivity values of 0.54-1 m indicated permeable reservoirs at depths of 1.5-2.5 km, and resistivity values of 290-550 m indicated geothermal rocks at depths of 4-10 km. The findings of this research are expected to enhance the understanding of geothermal energy as a renewable resource, thereby supporting the Sustainable Development program.

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

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.

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

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.

Analisa Lapisan Sedimen Bawah Permukaan Pada Pembangunan Jalan Elevated Danau Dendam Tak Sudah Kota Bengkulu Menggunakan Metode HVInv Setyowati, Yuni; Farid, Muchammad; Ismul Hadi, Arif; Helinnes, Putri; Refrizon, Refrizon; Hardiansyah, Debi; Gumanty, Usman; Raihana, Hana; Rahmat Al-Ansory, Andre; Taufiqurrahman Syah, Muhammad
Jurnal Ilmu Fisika Vol 16 No 2 (2024): September 2024
Publisher : Jurusan Fisika FMIPA Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jif.16.2.187-197.2024

Bengkulu City is situated within a subduction zone where the Indo-Australian and Eurasian tectonic plates converge, rendering the area highly susceptible to seismic activity. This study employs the microseismic method to assess seismic vulnerability and the subsurface rock structure at the Dendam Tak Sudah Lake Flyover Construction Site in Bengkulu City, which encompasses a swampy region. The microseismic method used was an inversion of the horizontal to vertical (H/V) spectral ratio (HV-Inv) for determining the dominant frequency (f0), amplification factor (A0), seismic sensitivity index (Kg), and shear wave velocity (Vs). The findings reveal that f0 in the study area range from 2.16 to 7.53 Hz, A0 vary from 0.40 to 3.79, and Kg values span from 0.03 to 6.04. The sedimentary layers exhibit an average thickness of 5-10 meters, with some locations showing significantly thicker sedimentary deposits. Notably, the highest seismic susceptibility is recorded at point T8. The Vs values range from 185.19 to 539.49 m/s, which are inversely proportional to the Kg values and indicate soil classifications varying from soft to medium. The overall seismic risk in the study area is moderate. These results offer key insights into geophysical and geological conditions in Bengkulu City, crucial for earthquake mitigation.

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