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All Journal Jurnal Rekayasa Geofisika Indonesia Jurnal Rekayasa Geofisika Indonesia
Jamhir Safani
Jurusan Teknik Geofisika, Universitas Halu Oleo
Computer Science & IT Earth & Planetary Sciences Engineering Physics

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Interpretasi Struktur Geologi Daerah Selatan Pulau Buton Menggunakan Data Gravitasi Satelit GGMplus Muhammad Nur Ahsan Zakir; Jamhir Safani
Jurnal Rekayasa Geofisika Indonesia Vol 3, No 01 (2021): Edisi April JRGI (Jurnal Rekayasa Geofisika Indonesia)
Publisher : Jurnal Rekayasa Geofisika Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Telah dilakukan penelitian pengukuran medan gravitasi untuk mengetahui pola sebaran anomali Bouguer dan mengidentifikasi struktur geologi di daerah selatan Pulau Buton. Pengukuran data medan gravitasi menggunakan satelit Global Gravity Model plus (GGMplus) dengan spasi antar titik pengukuran ~220 meter. Data yang digunakan berupa data medan gravitasi yang telah terkoreksi udara bebas, sehingga hanya perlu melakukan koreksi Bouguer dan koreksi medan untuk memperoleh anomali Bouguer lengkap di topografi. Selanjutnya dilakukan proyeksi ke bidang datar, kontinuasi ke atas, dan analisis Second Vertical Derivative (SVD). Hasil anomali Bouguer lengkap dan anomali lokal menunjukkan pola sebaran berarah timurlaut-baratdaya. anomali tinggi berada di bagian timurlaut dan baratdaya daerah penelitian sedangkan anomali rendah berada di bagian selatan, timur dan kawasan utara-baratdaya daerah penelitian. Anomali tinggi diduga disebabkan oleh keterdapatan potensi hidrokarbon berupa bitumen aspal yang berasosiasi dengan Formasi Tondo dan Formasi Sampolakosa. Anomali rendah di kawasan selatan disebabkan karena daerah tersebut didominasi oleh batuan yang berumur sangat muda (Formasi Wapulaka), sedangkan anomali rendah di kawasan utara-baratdaya mengindikasikan daerah cekungan yang berada di Selat Buton. Berdasarkan hasil analisis SVD pada anomali lokal, terdapat 10 sesar yang bisa diidentifikasi jenis sesarnya. Sesar A,B,E,G,H, dan I diidentifikasikan sebagai sesar turun, sedangkan sesar C,D,F, dan J diidentifikasikan sebagai sesar naik.
Interpretasi Data Mikrotremor Melalui Analisis Horizontal To Vertical Spectral Ratio (HVSR) untuk Mikrozonasi Bahaya Gempa Seismik di Kota Baubau Rudin; Jamhir Safani
Jurnal Rekayasa Geofisika Indonesia Vol. 6 No. 02 (2024): Edisi Agustus JRGI (Jurnal Rekayasa Geofisika Indonesia)
Publisher : Program Studi Teknik Geofisika FITK UHO

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56099/jrgi.v6i02.92

Abstract

Research has been carried out on seismic hazard microzonation in the city of Bau – bau using microtremor data. The aim of this research is to determine the seismic vulnerability index based on horizontal to vertical spectral ratio (HVSR) analysis and create a dominant frequency microzonation map (F0), dominant period map (T0), amplification factor map (A0), and seismic vulnerability index map (Kg) from microtremor data which can describe the level of vulnerability of an area to seismic hazards. Microtremor measurements were carried out using a portable three-component seismograph (TDS. 303), the data was analyzed with gepsy software via the HVSR method. The research results show that the distribution of dominant frequency values ​​(F0), ranges from 0.4795 Hz to 16.6383 Hz, dominant period values ​​(T0), ranges from 0.0601 seconds to 2.0854 seconds, amplification factor values ​​(A0), ranges from 1.2285 to 4.9043, and the seismic vulnerability index (Kg) value ranges from 0.1043 to 11.0276. The values ​​(F0), (T0), (A0), and (Kg) are interpreted by referring to literature data and surface geological maps of the research area. The results show that the study area has a small portion of sediment layers that are vulnerable to seismic hazards.
Estimasi Sistem Perlapisan pada Blok-A Area Panas Bumi Lainea Konawe Selatan Menggunakan Vertical Electrical Sounding (Ves) Konfigurasi Schlumberger Syafira Mpuhu; Jamhir Safani; Syamsul Razak Haraty
Jurnal Rekayasa Geofisika Indonesia Vol. 7 No. 02 (2025): Edisi Agustus JRGI (Jurnal Rekayasa Geofisika Indonesia)
Publisher : Program Studi Teknik Geofisika FITK UHO

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56099/jrgi.v7i02.19

Abstract

This research aims to estimate the layering system in the Lainea Geothermal area in South Konawe Regency. The apparent resistivity data obtained from the Pusat Sumber Daya Geologi (PSDG) measured in 2010 using the Schlumberger configuration was inversed with the particle swarm optimization (PSO) method. From the results of data inversion at both sounding points, it was found that there are five layers with different resistivity ranges. The first layer is a thin overburden near the surface with a thickness of 0.5 - 0.7m. The second layer is thought to be conglomerate rock. The third layer is interpreted as cap-rock with meta-sandstone lithology with a resistivity value range of 126.3<ρ<366 Ωm. The fourth layer with sandstone lithology is closely suspected as a fluid accumulation zone with a resistivity value range of 45.4<ρ<69 Ωm. The lowest layer with a resistivity value range of 261<ρ<500 Ωm is interpreted as metamorphic rock which is thought to act as an impermeable layer.
Identifikasi Sistem Perlapisan Blok – B Area Panas Bumi Lainea Konawe Selatan Menggunakan Metode Vertical Electrical Sounding (Ves) Konfigurasi Schlumberger Annisa Tiara Saputri; Jamhir Safani; Syamsul Razak Haraty
Jurnal Rekayasa Geofisika Indonesia Vol. 8 No. 01 (2026): Edisi April JRGI (Jurnal Rekayasa Geofisika Indonesia)
Publisher : Program Studi Teknik Geofisika FITK UHO

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56099/jrgi.v8i01.20

Abstract

Gravity forward modeling based on the Last–Kubik kernel requires intensive computation as the number of model blocks and observation points increases. This study analyzes the computational performance of Full Vectorization (FV) compared with Nested Loop (NL) without modifying the mathematical formulation of the Last–Kubik kernel. Experiments were conducted using synthetic models with 20 configurations ranging from 20,000 to 168,200 blocks. Algorithm performance was evaluated based on gravity-response consistency, computational time, and memory usage. Computational time was assessed using Total Execution Time (TET) and Mean Core Computational Time (MCCT) from 30 repetitions, while memory usage was evaluated using Kernel Workspace Memory Increase (KWMI). The results show that the FV and NL implementations produce numerically identical gravity responses, with a maximum absolute difference of 0 for the tested configurations. FV provides an MCCT speedup of approximately 6–7 times for small to medium-sized models, but the speedup decreases to 1.56 times at 168,200 blocks. In contrast, FV requires approximately 18 times more memory than NL. Regression analysis shows a very strong linear relationship between KWMI and the number of observation–block pairs. The results demonstrate that FV effectively accelerates gravity forward modeling but has scalability limitations due to its substantially higher memory requirements
Estimasi Model 3D Antar-Muka Basement Kawasan Panas Bumi Lainea-Konawe Selatan Berdasarkan Anomali Medan GravitASI Data GGMPLUS Andre Nico Carli Silalahi; Jamhir Safani; Al Rubaiyn
Jurnal Rekayasa Geofisika Indonesia Vol. 7 No. 03 (2025): Edisi Desember JRGI (Jurnal Rekayasa Geofisika Indonesia)
Publisher : Program Studi Teknik Geofisika FITK UHO

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56099/jrgi.v7i03.63

Abstract

This research was conducted in the South Konawe area, especially in other geothermal using satellite image data, namely the Global Gravity Model Plus (GGMPlus) which has been developed with high resolution and a distance between points of -220m. Several studies have been conducted basement 3D modeling using measurement data but have not found basement 3D modeling in the Lainea area based on GGmplus data.Gravity data modeling (residual anomaly) was inverted using the GRAV_D_In-based MATLAB program. The Grav_D_In program requires several parameters, namely anomaly depth estimation, area area, wavenumber range for low-pass filters, density contrast, and widowing. The result of the inversion of the basement interface 3D model has a depth ranging from 980m to 1540m. The results of the basement contour pattern overlay with the structural pattern show that the structural pattern partially follows the basement contour pattern. An overlay of the basement model of the study was carried out using field data in the topography, that the basement model intersected in the use of satellite image data with measurements. The second basement pattern intersects but has different depths
Co-Authors Al Rubaiyn Andre Nico Carli Silalahi Annisa Tiara Saputri Muhammad Nur Ahsan Zakir Rudin Syafira Mpuhu Syamsul Razak Haraty