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All Journal BERKALA FISIKA POSITRON Wahana Fisika : Jurnal Fisika dan Terapannya JGE (Jurnal Geofisika Eksplorasi) JURNAL ILMIAH PENDIDIKAN FISIKA AL BIRUNI Indonesian Physical Review
Ahmad Zaenudin
Jurusan Teknik Geofisika, Fakultas Teknik, Universitas Lampung
Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Physics

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Karakterisasi Zona Sliding Di Perbukitan Ranggawulung Subang Dengan Metoda Geolistrik Tahanan Jenis Susanto, Kusnahadi; Zaenudin, Ahmad
BERKALA FISIKA Vol 13, No 2 (2010): Berkala Fisika, Edisi Khusus
Publisher : BERKALA FISIKA

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Abstract

Subang Ranggawulung Hills is a road connecting Bandung- Subang which is landslide-prone. Landslides have occurred in the area and now the potential for ground movement is still visible which is characterized by crack and wave roads and buildings sideway. This study characterizes the sliding zone and the direction of movement of ground geoelectric resistivity method. Geoelectrical resistivity method to detect the existence of a sliding zone of the layer surface lapsed causes that caused Landslides. Of geoelectric resistivity cross-section indicates that the contact area between the layers with a certain slope at a depth of about 3-10 m below ground surface. Fields marked with a contact layer of low resistivity value of about 5-10 m which is consistent on all tracks. By observing these results can be seen that the hills Ranggawulung potential for the occurrence of landslides, although slow moving. Key words: landslides, low resistivity
Koreksi Gaya Berat Akibat Curah Hujan Pada Pengukuran Gaya Berat Mikro Antar-Waktu Lapangan Panas Bumi Kamojang 2006-2007 Zaenudin, Ahmad
BERKALA FISIKA Vol 13, No 2 (2010): Berkala Fisika, Edisi Khusus
Publisher : BERKALA FISIKA

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Abstract

Shallow groundwater level changes cause seasonal gravity anomaly. Changes in groundwater level is directly related to rainfall, when heavy rainfall, groundwater level rises rapidly and then declined gradually. Gravity anomaly due to the season is important to take into account noise. Changes in groundwater level due to rainfall is calculated using empirical equations, and the Gravity response calculated using the approach of an infinite Bouguer slab correction by entering the porosity factor. The rainy season in the Kamojang geothermal field occur between November to June and dry season between July to October. The highest rainfall in 24 hours occurred on December 8 by 75 mm. From the empirical calculations showed that changes in groundwater level due to rainfall period November 2006-June 2006 amounted to -1.502 m and July 2007-June 2006 amounted to +0.396 m. Based on the approach slab Bouguer corrected gravity anomaly not to cause inter-time respectively -18.89 and +5.98 mikrogal mikrogal for porosity of 30%. Changes in groundwater level is negative (a reduction of groundwater) caused gravity anomaly time inter-negative, and vice versa. Correction of the gravity anomaly due to inter-time rainfall should not be ignored because of the gravity anomaly at the time inter-geothermal field is usually small.   Key words: rainfall, groundwater level, inter-period gravity anomaly
PEMODELAN 2D DAN 3D GEOLISTRIK TOMOGRAFI UNTUK INTERPRETASI BIDANG GELINCIR DAN ARAH ALIRAN AIR PADA STRUKTUR BAWAH PERMUKAAN REL KERETA API DI BATURAJA, SUMATERA SELATAN Zaenudin, Ahmad; Dani, Ilham
Wahana Fisika Vol 4, No 2 (2019): December
Publisher : Universitas Pendidikan Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17509/wafi.v4i2.20327

Abstract

Monitoring kondisi bawah permukaan rel kereta api merupakan bagian penting dalam operasional perkeretaapian. Penelitian ini bertujuan untuk mendeliniasi lapisan bawah permukaan rel kereta api yang sering terjadi pergeseran dan longsoran dengan metode geolistrik dipole-dipole secara tomografi. Pemodelan 2D dan 3D geolistrik diterapkan untuk menginterpretasi bidang gelincir dan arah aliran air.  Model 2D dapat mengidentifikasi 3 lapisan utama, yaitu lapisan perkerasan tanah di bagian atas, lapisan dengan resistivitas rendah (4-60 Ohm.meter) dan lapisan badrock (100-500 Ohm.meter). Lapisan dengan reistivitas rendah diduga mengandung air sebagai penyebab tanah longsor, dimana bidang batas lapisan ini dialasi oleh bedrock yang berada pada kedalaman antara 5-17 meter yang diduga sebagai bidang gelincir. Model 3D dapat mendeliniasi arah aliran air di bawah permukaan rel kereta api, yaitu berarah Timur Laut – Barat Daya melintasi bagian bawah rel kereta api.
IDENTIFIKASI ORIENTASI REKAHAN MIKRO AREA PANAS BUMI MONTE AMIATA BERDASARKAN ANALISIS STUDI SHEAR WAVE SPLITTING Irfan - Hanif; Ahmad Zaenudin; Nandi Haerudin; Rahmat C Wibowo
Indonesian Physical Review Vol. 3 No. 2 (2020)
Publisher : Universitas Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1021.678 KB) | DOI: 10.29303/ipr.v3i2.56

Abstract

Shear Wave Splitting is an application of seismic wave to analyse the anisotropy level of a certain medium. Generally, shear wave propagation through a rock formation will be polarized (φ) into two parts especially when the medium structures are different, such as fracture. The polarized shear wave which is perpendicular to fracture will propagate slower than the wave that propagates parallel to the fracture. The delay time (δt) of both wave is proportional with the fracture intensity along the wave propagation from the source to the station. The description regarding fracture orientation can be obtained by analysing both Shear Wave Splitting parameters (φ and δt), and this information is adequately important in geothermal exploration or exploitation phase at Mt. Amiata. Based on the result of this research, the micro earthquake source is focused on the east to the south area and spread along 3 earthquake stations. The existence of micro earthquake source is mainly focused at the depth of 1 to 4 km. In addition, the polarization direction of each earthquake station at the geological map shows a dominant fracture orientation consistently at NW-SE. All of the three stations also show that the polarization direction is integrated to the local fault existence in the subsurface. Furthermore, the research shows that the high intensity fracture distribution occurred at MCIV station area in the southern part of research location. Meanwhile, the low intensity fracture distribution occurred at ARCI and SACS station area in the western and the eastern part of research location. The high value of fracture intensity accompanied by the high amount of structure intensity, strengthen the prediction of the high anisotropy existence which potentially tends to the high permeability presence at the area.Keywords: shear wave splitting, anisotropy, fracture, geothermal, polarization direction, fracture intensity.
ANALISIS RESERVOAR MIGAS (SANDSTONE) MENGGUNAKAN MULTIATRIBUT SEISMIK PADA LAPANGAN TG12, CEKUNGAN BARITO, KALIMANTAN SELATAN Edo Pratama; Bagus Sapto Mulyatno; Ahmad Zaenudin
Jurnal Geofisika Eksplorasi Vol 5, No 1 (2019)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v5i1.19

Abstract

The study using multi attribute seismic has been done on TG12 field which situated at Lower Foreland Formation, Barito Basin dominated by sandstone on layer area of the target X. The objective of the study is to map the sandstone reservoir by predict distribution value of gamma ray log, neutron porosity, and density which goes through wells such as FM1, FM2, FM3, and FM4 on seismic data. Total attribute that is being used by step wise regression method by considering validation error. Multiattribute process only applied on FM2, FM3, and FM4 wells, whereas FM1 is used as a test well to determine the correlation value between seismic data and log data that is being used. In addition, from well test correlation showing great correlation result of neutron porosity log and density log both obtain the correlation around 0.6322 and 0.6557 while the gamma ray log obtain low correlation that is 0.1647 towards multi attribute result. The processing result of multi attribute obtained distribution of sandstone with gamma ray estimation range value of 65-75.8API, neutron porosity estimation range value 0.15-0.2262, while density estimation range value 2.4308-2.77gr/cc.
PEMANTAUAN PROSES INJEKSI AIR PADA LAPANGAN “SMR” CEKUNGAN SUMATERA TENGAH BERDASARKAN DATA ANOMALI TIME-LAPSE MICROGRAVITY Ahmad Zaenudin; Dian Pratiwi; Agung Wiyono
Jurnal Geofisika Eksplorasi Vol 4, No 1 (2018)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v4i1.10

Abstract

There had been done a regional research about monitoring of injection process in "SMR" field of Central Sumatera Basin using microgravity method. The time-lapse microgravity method is the development of the gravity method (x, y, z) by adding the fourth dimension of time (t). Monitoring is carried out on production fields that have performed EOR (Enchanced Oil Recovery) ie the process of injecting water into the reservoir to push and drain the remnants of oil in the pores of the reservoir rock to the production well. The microgravity data processing is done by finding the difference between observed gravity values between the first and the second measurements, then performing the spectral analysis to separate the anomaly at reservoir depth and noise. The time-lapse microgravity anomaly has a value of -132.28 μGal to 54.89 μGal. Positive anomalies are related to the injection process, whereas the negative anomalies are related to the production process in the study area. Filtering analysis shows that there are two zones of fluid dynamics, which is due to the process of surface water dynamics (groundwater above reservoir) and that occurs in the reservoir. Fluid reduction zones occur in areas with more production wells than injection wells. Density reduction occurs in the reservoir layer at a depth of 600 m to 1000 m with a maximum reduction value of -3.1x10-3 gr / cm3. The gravity time-lapse inversion model shows the existence of several injection wells that are less effective and therefore need to be stopped injecting.
Studi Identifikasi Struktur Geologi Bawah Permukaan Untuk Mengetahui Sistem Sesar Berdasarkan Analisis First Horizontal Derivative (FHD), Second Vertical Derivative (SVD), Dan 2,5D Forward Modeling Di Daerah Manokwari Papua Barat Ahmad Zaenudin; Shiska Yulistina
Jurnal Geofisika Eksplorasi Vol 4, No 2 (2018)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v4i2.15

Abstract

In general, Manokwari has a geological structure that is in the form of a folding area found in the highlands of the mountains. Among the creases, there is a fault up and the fault down. In coastal or marine areas found many reefs and corals. The study of gravity was conducted in the Manokwari area of West Papua with the aim to know the subsurface geological structures based on FHD (First Horizontal Derivative), SVD (Second Vertical Derivative) and 2.5D Forward Modeling on the residual anomaly maps of the study area. The results showed that the research area has Bouguer Anomaly value ranged from 4 mGal to 96 mGal with the low anomaly at the left side of the research area lengthwise relatively in north-west to south-east direction, the middle-value anomaly spreads in the west-east area of research area, high anomaly scattered in the northern part of the research area. The results of the 2.5D subsurface modeling and the SVD and FHD analysis indicated the presence of a Thrust Fault on the C-C’ cross-section, on the B-B’ cross-section there is a Diorite Lembai intrusion with the density value is 2.75 gr/cc, whereas the A-A' cross-section which intersects with Sorong fault were not found any fault or rock intrusion based on observed gravity data of the research area.
DELINEATION OF SUBSIDENCE IN THE ALTERATION ZONE IN ULUBELU GEOTHERMAL FIELD BASED ON INTERFEROMETRY SYNTHETIC APERTURE RADAR TIME SERIES Ahmad Zaenudin; Ilham Tri Putra Sofiyadin; Rachmat Arief
Jurnal Geofisika Eksplorasi Vol 6, No 3 (2020)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v6i3.76

Abstract

Ulubelu is a geothermal region managed by Pertamina Geothermal Energy (PGE) located in Mount Kukusan, Sula, Kabawok, Kuripan and Rindingan. The learning of subsidence is required for disaster mitigation. This research use 33 SAR data of Sentinel1-A which bundled for generate an APS and then using multi temporal analysis to generate InSAR time series from 2018 September to 2017 April. InSAR time series can detect indication of subsidence practically and quickly. Decrease velocity of subsidence in the Ulubelu geothermal region is an average of 3,3 mm/yr (X=453.558, Y=9.412.437, 48 S zone. This subsidence is domination by altered rocks compaction. In the other hand, the geological structure (faults) and lithology also surface loading affected the subsidence. Pekon Gn. Tiga, Karang Rejo, Muara Dua and Pagar Alam are the worst of subsidence area. Mitigation must to be clear early for areas that have the worst subsidence in Ulubelu geothermal field.
2D gravity qualitative modeling to identify bedrock and volcanic rocks in South Lampung region Ahmad Zaenudin; I Gede Boy Darmawan; George Laimeheriwa
Jurnal Ilmiah Pendidikan Fisika Al-Biruni Vol 9, No 1 (2020): Jurnal Ilmiah Pendidikan Fisika Al-Biruni
Publisher : Universitas Islam Negeri Raden Intan Lampung, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1026.835 KB) | DOI: 10.24042/jipfalbiruni.v9i1.5859

Abstract

Gravity measurement has been conducted in South Lampung area to study the characteristics of the distribution of bedrock and igneous rocks, especially those that can be utilized for development in the National Strategic Area of the Sunda Strait. This study uses a 2D qualitative modeling method and utilizing spectrum analysis of complete Bouguer anomaly data. Based on the result of modeling of residual gravity anomaly, it was found that the intrusion pattern on Sulan granitoid pluton and surrounding plutons showed a significant intrusion of the body and scattered in some Tarahan area. 2D qualitative modeling shows Paleozoic metamorphic rocks are responsible as bedding rocks, and the spread was identified scattered throughout the study area, although it cannot be ascertained whether the bedrock in the Bakauheni area is precisely the same rock as the bedrock in Tarahan area. Meanwhile, Quaternary volcanic rocks are still dominated by tuffaceous sandstone and breccia. This method also confirms that andesite lava is commonly found as a product of the eruption of Mount Rajabasa and Pre-Rajabasa in the Bakauheni region. Nevertheless, some potential of basaltic andesite rocks can be obtained in monogenetic volcanic zones exposed around the foot of Mount Rajabasa.
2D gravity qualitative modeling to identify bedrock and volcanic rocks in South Lampung region Ahmad Zaenudin; I Gede Boy Darmawan; George Laimeheriwa
Jurnal Ilmiah Pendidikan Fisika Al-Biruni Vol 9, No 1 (2020): Jurnal Ilmiah Pendidikan Fisika Al-Biruni
Publisher : Universitas Islam Negeri Raden Intan Lampung, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/jipfalbiruni.v9i1.5859

Abstract

Gravity measurement has been conducted in South Lampung area to study the characteristics of the distribution of bedrock and igneous rocks, especially those that can be utilized for development in the National Strategic Area of the Sunda Strait. This study uses a 2D qualitative modeling method and utilizing spectrum analysis of complete Bouguer anomaly data. Based on the result of modeling of residual gravity anomaly, it was found that the intrusion pattern on Sulan granitoid pluton and surrounding plutons showed a significant intrusion of the body and scattered in some Tarahan area. 2D qualitative modeling shows Paleozoic metamorphic rocks are responsible as bedding rocks, and the spread was identified scattered throughout the study area, although it cannot be ascertained whether the bedrock in the Bakauheni area is precisely the same rock as the bedrock in Tarahan area. Meanwhile, Quaternary volcanic rocks are still dominated by tuffaceous sandstone and breccia. This method also confirms that andesite lava is commonly found as a product of the eruption of Mount Rajabasa and Pre-Rajabasa in the Bakauheni region. Nevertheless, some potential of basaltic andesite rocks can be obtained in monogenetic volcanic zones exposed around the foot of Mount Rajabasa.
Co-Authors Agung Wiyono Bagus Sapto Mulyatno Dani, Ilham Dian Pratiwi Edo Pratama George Laimeheriwa I Gede Boy Darmawan Ilham Tri Putra Sofiyadin Irfan - Hanif Karyanto, Karyanto Kurniasih, Aulia Kusnahadi Susanto Nandi Haerudin Rachmat Arief Rahmat C Wibowo Rananda, Eko Shiska Yulistina Suharno Suharno Wibowo, Rahmat Catur