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Pemetaan Potensi Kerentanan Gempabumi Pada Kota Bengkulu Menggunakan Data Mikrotremor dan Metode Analytical Hierarchy Process Arif Ismul Hadi; Muchammad Farid; Refrizon Refrizon; Budi Harlianto; Nurul Hudayat; Malik Krisbudianto
Jurnal Fisika FLUX Vol 18, No 2 (2021): Jurnal Fisika Flux: Jurnal Ilmiah Fisika FMIPA Universitas Lambung Mangkurat
Publisher : Lambung Mangkurat University Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1102.835 KB) | DOI: 10.20527/flux.v18i2.9479

Abstract

ABSTRAK- Kota Bengkulu merupakan daerah yang sangat rawan terhadap ancaman gempabumi. Salah satu upaya mengurangi dampak bencana gempabumi adalah melakukan analisis potensi tersebut berdasarkan data mikrotremor dan metode pembobotan statistik. Penelitian ini bertujuan memetakan dan menganalisis daerah-daerah yang rentan mengalami ancaman bahaya gempabumi. Penelitian ini dilakukan menggunakan data sekunder dan survei lapangan. Data sekunder bersumber dari penelitian-penelitian terkait, sedangkan data survei lapangan berupa data mikrotremor menggunakan metode Horizontal to Vertical Spectral Ratio (HVSR). Alat yang digunakan untuk survei lapangan berupa broadband seismometer PASI Gemini-2 triaxial geophone dengan natural freq. 2 Hz ± 10%, berat 2 kg (s.n.: 12/004). Akusisi data lapangan dilakukan selama 30 menit (360.000 samples) per titik pengukuran dengan sampling rate 5 ms (200 Hz). Selanjutnya, tumpangsusun hasil pengolahan data sekunder dan lapangan menggunakan metode pembobotan statistik Analytical Hierarchy Process (AHP), sehingga diperoleh peta potensi kerentanan gempabumi di wilayah studi. Berdasarkan hasil analisis yang ditunjukkan dalam peta kerentanan gempabumi di daerah Kota Bengkulu dalam penelitian ini, Kecamatan Gading Cempaka, Kecamatan Singaranpati, Kecamatan Selebar, sebagian kecil Kecamatan Ratu Agung, dan Kecamatan Muara Bangkahulu adalah daerah yang mempunyai potensi kegempaan tinggi, sedangkan Kecamatan Selebar adalah daerah yang mempunyai potensi kegempaan rendah. Oleh karena itu untuk daerah berisiko tinggi perlu lebih diwaspadai dan perlu perencanaan pembangunan yang mengacu kepada standar risiko bencana. ABSTRACT− Bengkulu City is an area that is very prone to earthquake threats. One of the method to reduce the impact of an earthquake disaster is to conduct a potential analysis based on microtremor data and statistical weighting methods. This study aims to map and analyze the areas have the vulnerability to experience an earthquake hazard. This study was conducted using secondary data and field surveys. Secondary data comes from related studies, while field survey data is in the form of microtremor data using the Horizontal to Vertical Spectral Ratio (HVSR) method. The instrument used for the field survey was a broadband seismometer PASI Gemini-2 triaxial geophone with natural freq. is 2 Hz ± 10%, weight is 2 kg (s.n .: 12/004). Field data acquisition was carried out for 30 minutes (360,000 samples) per observation point with a sampling rate of 5 ms (200 Hz). Furthermore, the overlay of the results of secondary and field data processing uses the statistical weighting method of Analytical Hierarchy Process (AHP), in order to obtain a map of potential the seismic vulnerability in the study area. Based on the results of the analysis shown in the seismic vulnerability map in the Bengkulu City area in this study, Gading Cempaka Sub-district, Singaranpati Sub-district, Selebar Sub-district, a small part of Ratu Agung Sub-district, and Muara Bangkahulu Sub-district were areas that had a high seismic vulnerability, while Selebar Sub-district were areas that had low seismic vulnerability. Therefore, high-risk areas need to be more vigilant and need development planning that refers to disaster risk standards. 
Interpretasi Tingkat Kekerasan Batuan Bawah Permukaan di Daerah Rawan Gempa Bumi Kota Bengkulu Arif Ismul Hadi; Refrizon Refrizon; Halauddin Halauddin; Liza Lidiawati; Paisal Edo
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 11, No 1 (2021): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v11i1.46525

Abstract

Bengkulu City is located in the subduction zone of the Indo-Australian and Eurasian plates, so it is prone to earthquake. To anticipate the impact of earthquake, disaster mitigation can be carried out, one of which is a study of the level of rock hardness in the area. This study aims to determine the level of rock hardness based on seismic wave velocity in several rock formations and to determine which rock formations have the potential to cause vulnerability to earthquakes. Field data acquisition uses the seismic refraction method with time-term inversion technique. The data obtained in the field are processed to obtain a 2-D cross-section of the subsurface seismic wave velocity values. The study results show that the level of rock hardness depends on the type of rock formation. The Andesite Rock Formation Unit (Tpan) has the highest level of hardness, while the transitional area between the Alluvium Rock Formation Unit (Qa) and the Swamp Sedimentary Rock Formation Unit (Qs) has the lowest level of hardness.
Pemodelan Struktur Permukaan 2D Kota Bengkulu Menggunakan Metode Geomagnet Rama Ramdani; Refrizon Refrizon; Elfi Yuliza; Darmawan Ikhlas Fadli; Muhamad Hasan
Jurnal Penelitian Pendidikan IPA Vol 9 No 2 (2023): February
Publisher : Postgraduate, University of Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jppipa.v9i2.2914

Abstract

Research on 2D modeling of the subsurface structure of the Bengkulu city area was carried out using the geomagnetic method. In this study, we collected data from 130 measurement points using a set of Proton Procession Magnetometers (PPM) to obtain the total magnetic field value. The measurement data were processed by making corrections of daily variations and IGRF (International Geomagnetic Reference Field). We conducted data correction to contour the total magnetic field anomaly. After that, the contour of total magnetic field anomaly was used for the reduction to the poles. This research results from the total magnetic field anomaly show a pair of positive and negative closures. Cross-sections were made on the positive and negative closure pairs to determine the subsurface structure of the area by making a 2-dimensional (2D) model using Mag2DC software. The interpretation of the 2D modeling results shows that three rock layers are continuously arranged. The average susceptibility value of the first layer is 0.00001 cgs which is a sandstone layer at a depth of 0-400 meters; the second layer has an average susceptibility value of 0.002 cgs which is dominated by clay at a depth of 400-700 meters, and; the third layer has an average susceptibility value of 0.006 cgs which is a basalt rock layer at a depth of 700-1000 meters.