Accepted manuscripts
Identification of Areas at Risk of Abrasion Application of Electrical Resistivity Tomography (ERT) Method on Nangai Beach, North Bengkulu
Bayu Saputra, Suhendra*, Halauddin, Liza Lidiawati, and Shyaira Marcelina
Abstract: A study of the underground structures in areas prone to abrasion of Nangai Beach, North Bengkulu Regency. In this study, 2D images of the subsurface structure at the Nangai Beach site were obtained using the Wenner-Schlumberger configuration, while 3D representations were obtained using the Electrical Resistivity Technique (ERT). To protect coastal materials, the main objective of this research is to identify rock types that are resistant to seawater erosion and measure the resistivity of rocks that can be eroded. In addition, software (ERT LAB 64, View Lab 3D and Res2Dinv) was used to analyze the data by processing it and displaying an image of the resistivity value. The interpretation results show that the coastal zone of the study area is dominated by clays with resistivity (> 34 m). The shoreline of Nangai beach consists of shale clay (>> 437 m). Rocks having a resistivity value (437 m) are not easily eroded by erosion in shale clay. This is because the rocks known as shale clay have low porosity, resulting in compact rock density. Restoring damaged soil and planting trees near the coast are two ways to slow down the abrasion process.
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Effect of Carbonization Temperature on Pore Formation and Adsorption Ability of Coconut Shell Activated Carbon with KOH Activator
Arinda Yukashima Putri Prahesti, Sheilla Rully Anggita*, and Hamdan Hadi Kusuma
Abstract: Activated carbon derived from coconut shells has great potential as an adsorbent for water purification due to its high porosity. This study investigates the effect of carbonization temperature on pore formation and adsorption capacity of coconut shell activated carbon. Carbonization was conducted at temperatures rang-
ing from 500◦C to 700◦C for 2 hours, followed by chemical activation using 3M KOH solution. The activated carbon was then filtered, washed until neutral pH (± 7), and dried. Characterization was carried out using the BET method to analyze surface area and pore volume, while adsorption capacity was determined using a UV-Vis spectrophotometer with methylene blue as the adsorbate. The results show that increasing the carbonization temperature enhances pore development, as indicated by higher surface area and pore volume. The highest surface area and pore volume were obtained at 700◦C, reaching 426.692 m2/g and 2.414 cc/g, respectively. Correspondingly, the highest adsorption capacity was also observed at 700◦C, with a value of 3957.15 mg/g. These findings suggest that carbonization temperature plays a critical role in optimizing the physical characteristics and adsorption performance of coconut shell-based activated carbon.
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Estimation Earthquake Source Parameters in Mentawai Island Region Using Moment Tensor
Fahmia Zuwidhatul Husna, Sungkono, Muhammad Nurul Fahmi, Eko Minarto, and Saifuddin
Abstract: The Mentawai Islands is a seismically active zone that often experiences earthquakes due to the interaction of tectonic plates, so it is necessary to analyze the earthquake source parameters to understand its characteristics. This study aimed to determine earthquake source parameters for events of M w ≥ 5.5 that occurred in 2023 using moment tensor inversion. Three-component waveform data from the GEOFON network were analyzed in the time domain, filtered within a frequency range of 0.01 to 0.025 Hz. The inversion yielded variance reduction (VR) values above 70% (88.24%, 81.98%, 94.05%, and 73.16%), indicating a good fit between observed and synthetic waveforms. The results of waveform data analysis show that the earthquake in the study area was caused by tectonic activity characterized by the percentage of Double-Couple (DC) more dominant than Compensated Linear Vector Dipole (CLVD), at shallow depths. Comparison with earthquake catalogs (GCMT, USGS, and GFZ) showed agreement, supported by Kagan angle values below 60◦. In addition, the focal mechanism of the waveform data analysis indicated that the type of fault that causes the earthquake in the study area was a reverse fault.
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Lithological Identification using Geoelectric Method in Landslide Area in Bengle Village
Icha Khaerunnisa, Andi, Nugroho Budi Wibowo, and Thaqibul Fikri Niyartama
Abstract: Dlepih Village, specifically in Bengle Hamlet, is an area that experienced a landslide disaster on November 28, 2017. This landslide disaster occurred in a residential area, resulting in the death of 2 people, necessitating mitigation measures. One of the initial steps in mitigation is to identify the lithology in the landslide area. This study aims to determine the lithology in the landslide area using the Dipole-Dipole resistivity geoelectric method. The resistivity method is used to investigate the subsurface structure of the earth by measuring the resistivity of rock or soil. The mechanism of this method relies on the flow of electric current and the measurement of potential difference, and is calculated based on a certain electrode configuration to obtain a picture of underground resistivity. Data was acquired using a set of Naniura Resistivity Meter instruments on four measurement lines. The measurement paths are located in the Semilir Formation, which consists of sedimentary rocks. The research results show that the landslide area consists of soil layers with a resistivity value of 2.32 Ωm 6.69 Ωm and a thickness of 1.26 m - 11.39 m, claystone layers with a resistivity value of 6.69 Ωm - 160 Ωm and a thickness of 11 m - 40.5 m, and andesite rock layers with a resistivity value of more than 160 Ωm and a thickness of 5.25 m - 37.71 m.
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2D Magnetotelluric (MT) Modelling for Geothermal System Interpretation
Eko Minarto, Mohammad Istajarul Alim, and Ahmad Zarkasy
Abstract: Geothermal systems are areas beneath the earth’s surface that store circulating heat energy. The heat energy stored in the geothermal system can be utilized by humans as an environmentally friendly alternative energy. Determining the geothermal system area requires geophysical exploration methods that have deep
enough penetration and can distinguish soil structures based on the value of resistivity. One method that is effective in determining geothermal systems is the magnetotelluric (MT) method. This method receives electric and magnetic field signals from the induction of subsurface rocks to the electromagnetic wave activity of solar storms and lightning. The signal is then processed to produce a resistivity value. This type of resistance data can then present the structure of the geothermal system, including impermeable rocks, reservoirs and magmatic intrusion zones. This study also collaborated with supporting geological and geochemical data. The results of the magnetotelluric method analysis for the geothermal system of this study area are suspected to have capsbrocks with a resistivity of less than 10 m spread near the surface. Reservoirs that have a resistivity of 10-40 m are located at a depth of about 1000 m below the surface based on the interpretation of all data.
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Tsunami Modeling In The Mentawai Island As A Study Material For Disaster Mitigation (Case Study: Mentawai Earthquake, October 25, 2010)
Sayyidatul Khoiridah, Septa Erik Prabawa, Pamudi, Rama Saputra Danta
Abstract: There was an earthquake in Mentawai on October 25, 2010 which resulted in 509 deaths, 17 people injured, and 11.425 people displaced. Based on this, tsunami modeling was conducted using L-2008 software. This study aims to determine the value of the earthquake source mechanism and conduct tsunami modeling. Tsunami modeling includes earthquake source modeling as a tsunami generator (source modeling), tsunami wave propagation modeling (ocean modeling), and tsunami height modeling (run-up modeling). In this study, bathymetry data and earthquake source mechanism data from the USGS agency were used. The calculation results showed that the Mentawai earthquake had a fault length of 218,78 km, fault width of 45,70 km, and slip of 3,84 m. While the results of tsunami modeling show that the vertical displacemeht value obtained is the maximum value of 1,55 m and the minimum value is -1,55 m. The ocean modeling results show that the tsunami waves reached Sipora Island, North Pagai, and South Pagai at 20 minutes and 50 seconds. While the simulation results of tsunami run up modeling show that the maximum run up is at Sabeugunggu bay with run up value of 6,34 meters. Tsunami run up modeling has an RMSE value of 0,73.
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Relativistic Quantum Brayton Engine Based on Two Non-Interacting Dirac Particles in a One-Dimensional Potential Well
Titis Qorin Nabila, Heru Sukamto, and Agus Purwanto
Abstract: A quantum heat engine converts heat into work based on the principles of quantum thermodynamics.This study investigates a quantum heat engine composed of two Dirac particles confined in a one-dimensional potential well. The potential well is limited to three discrete energy levels, and the two non-interacting Dirac particles are treated as identical. The system operates under a quantum Brayton cycle, consisting of isobaric and adiabatic processes. The total work output is calculated using the energy levels derived from the relativistic Dirac equation. The efficiency curve is obtained by plotting a theoretical expression as a function of the ratio LA/λ, where λ is the Compton wavelength. The efficiency increases monotonically with LA/λ, approaching an asymptotic maximum, and is further enhanced by larger values of the parameter α, which drive the engine toward near-optimal performance.
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Radiation Attenuation Properties of La2O3-Modified Bismuth Borate Glass for Gamma Shielding Applications
Oki Ade Putra, and Rin Hafsahtul Asiah
Abstract: The increasing demand for transparent, non-toxic, and environmentally friendly alternatives to conventional gamma radiation shielding materials, such as lead and concrete, has driven the development of glass-based shielding systems. This computational study investigates the radiation shielding performance of bismuth borate-based glass systems modified with varying concentrations of lanthanum oxide (La2O3). The glass samples were formulated with the composition (40–x)B2O3–25Bi2O3–20Na2O–15ZnO–xLa2O3, where x = 0, 3, 6, 9, and 12 mol%. Shielding parameters, including mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP) were evaluated through theoretical calculations using the XCOM software developed by NIST, which computes photon cross-sections based on the elemental composition of each sample, over the photon energy range of 0.01–15 MeV. The results showed that increasing La2O3 concentration led to a significant improvement in shielding effectiveness, marked by higher MAC and LAC values, and lower HVL, TVL, and MFP values—especially at low to intermediate photon energies. At 0.662 MeV, The sample with the highest La2O3 content (x = 12 mol%) showed an MFP value of 1.903 cm, significantly lower than RS-253-G18 (4.800 cm) and synthetic borax glass (5.500 cm). This represents a 60.35% and 65.4% reduction in MFP, respectively. Therefore, the x = 12 mol% sample demonstrated enhanced attenuation performance relative to the benchmark materials. These results suggest the potential of La2O3-modified bismuth borate glass as a candidate for future gamma radiation shielding applications, particularly in nuclear medicine, although further experimental validation is required to confirm its effectiveness, transparency, and environmental safety.
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Aloe vera and Silicone Oil Based Coating to Reduce Wettability of Glass
Maya Shofani, Suparno
Abstract: Aloe vera is the herbal plants that has various uses, one of which is as an edible coating to maintain durability. Silicone oil is also a liquid that is airtight and is commonly used as a coating material in various fields. This research develops a coating material that can reduce wettability on the glass surface. The study was conducted by making 5 samples of liquid A1 - A5 with variations in composition to see which liquid has the best ability to reduce wetness. A good surface has hydrophobic properties, namely being resistant to air. The coating technique on the glass was carried out using the deep coating method until the surface was dry and the contact angle of the glass surface droplets was measured using ImageJ software. The results showed that the media without a coating had hydrophilic properties with an average contact angle of 23.76 while the five variations of liquid were able to reduce wetness on the glass surface with the highest contact angle reaching 83.22 ° and the lowest contact angle of 46.53 °. In all sample A1 to A5 were able to reduce wetness and increase the contact angle more than 2 times.
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