Andre Rahmat Al Ansory
Program Studi Geofisika, Jurusan Fisika, Universitas Bengkulu

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DELINEASI NILAI RESISTIVITAS DI LAPANGAN PANAS BUMI TAMBANG SAWAH MENGGUNAKAN METODE MAGNETOTELLURIK Andre Rahmat Al Ansory; Hana Raihana; Vinki Loverly Pritama; Welly Saputri; Faritz Bagda Maghribi; Muchammad Farid; Arif Ismul Hadi; Halauddin; Budi Harlianto; Nanang Sugianto
Buletin Sumber Daya Geologi Vol. 18 No. 3 (2023): Buletin Sumber Daya Geologi
Publisher : Pusat Sumber Daya Mineral Batubara dan Panas Bumi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47599/bsdg.v18i3.386

Abstract

The subsurface structure of the geothermal field in Desa Tambang Sawah has been mapped. This research aims to delineate the resistivity values in the area of Tambang Sawah Village, Lebong Regency, Bengkulu Province based on magnetotelluric measurements which can later identify low, medium, and high resistivity values to interpret geothermal in the research area. The magnetotelluric (MT) method with electrical and magnetic sensors is used to collect data in the field. There are two electrical sensors in horizontal direction (Ex, Ey) and three magnetic sensors in horizontal direction. (Hx, Hy) and vertical (Hz). The results obtained from this study are that resistivity values of 20-50 ohm.m are considered as reservoirs, while resistivity of 0.26-0.8 ohm.m is considered as caprock, and resistivity greater than 300 ohm.m is considered as hot rock.
Investigation of Sediment Layer Thickness Estimation at Bengkulu University Hospital Based on Microtremor Data Andre Rahmat Al Ansory; Hana Raihana; M Farid; Arif Ismul Hadi
JURNAL GEOCELEBES Vol. 8 No. 1: April 2024
Publisher : Departemen Geofisika, FMIPA - Universitas Hasanuddin, Makassar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20956/geocelebes.v8i1.28144

Abstract

Bengkulu is the capital of Bengkulu Province and is located in the subduction zone between the Eurasian and Indo-Australian plates. Bengkulu is also close to the major faults of Sumatra, namely the Musi fault, the Ketahun fault, and the Manna fault. Therefore, regional planning and infrastructure development for earthquake mitigation is necessary. The purpose of this study is to estimate the thickness of the sedimentary layers in the construction zone of Bengkulu Hospital during the earthquake attenuation phase. This study is conducted by surface geological analysis using the HVSR method; data analysis using microtremor data. The microtremor data were analyzed using the HVSR method to obtain the amplification value (A0) and the dominant frequency (f0). HVSR analysis gave dominant frequency (f0) values from 5.1 to 5.8 Hz, amplification (A0) from 1.64 to 5.91 times, and dominant period (T0) from 1.49 to 2.81 seconds. The values of A0, f0, T0 are interpreted with reference to the literature and surface geology as a moderate risk of seismic vulnerability, characterized by moderate to weak sedimentation and moderate amplification values.
Identification of Sub-Fault Zone Using Magnetotelluric Inversion (Case Study: Ketaun Fault, Lemeu Village, Lebong Regency) Nurul Ilmi Rahmawati; Muchammad Farid; Arif Ismul Hadi; Andre Rahmat Al Ansory
JURNAL GEOCELEBES Vol. 8 No. 2: October 2024
Publisher : Departemen Geofisika, FMIPA - Universitas Hasanuddin, Makassar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.70561/geocelebes.v8i2.34588

Abstract

Lemeu Village, Lebong Regency, borders the Bukit Barisan Mountain range and is crossed by the Ketaun Fault, which causes a high level of seismic activity, so it is necessary to conduct research on the potential existence of the Ketaun sub-fault as one of the efforts to mitigate natural disasters such as earthquakes. The Magnetotelluric method utilises the earth's natural electromagnetic field, which is used to determine the distribution of resistivity in the subsurface using the ADU-07e Magnetotelluric tool with two horizontal electrical sensors (Ex, Ey) and three horizontal (Hx, Hy) and vertical (Hz) magnetic sensors and uses seven research points with an interval of 1 km. Data processing uses MAPROS software to convert data from the time domain to the frequency domain and ZONDMT2D to obtain subsurface resistivity values. The results obtained from this study are 2D magnetotelluric cross sections showing a zone with low resistivity values between research points P4 and P5 which is thought to be a new fault zone with resistivity values ranging from 1.3 – 6.1 Ωm from a depth of 2.5 km to a depth of 10 km. The zone is assumed to be a new fault that is a branch of the Ketaun fault.