Despite being densely populated and economically thriving, the northern coast of Java, specifically Pekalongan, encounters significant challenges to further development, notably land subsidence. Since the late 2000s, these hazards have become increasingly evident, causing infrastructure damage and displacing residents. Alluvial deposits are formations that provide insight into unconsolidated sediment affecting land subsidence. This study integrated land subsidence in alluvial deposits at nine Conventional Deep Pipe Monitoring (CDPM) spread between 2021 and 2025, Standard Penetration Test (SPT) results, geotechnical analysis, including Compressibility Index (Cc), and Activity Ratio (Ac) of undisturbed samples to assess the mechanisms of subsidence and spatial variability. The alluvium formation observation results are separated into three groups: fluvial deposit group 1, marsh-swamp deposit group, and fluvial deposit group 2. The average SPT test was the softest, measuring 8.9 in Wonokerto and 11.1 in Kandang Panjang, for the biggest CDPM decrease of -3.89 cm/year in Wonokerto and -3.24 cm/year in Tirto annually. Wonokerto and Depok have the biggest clay sediment accumulations, measuring 43.3 m and 43 m, respectively. Then, at depths approximately 10 m to 22 m below the surface, laboratory testing revealed that the highest values for (Cc) are 0.1 to 0.7, and (Ac) are 1.3 to 1.5. The study findings show that areas with thick soft clay layers and high compressibility exhibit the highest subsidence rates, exceeding more than -2.5 cm/year in the central northern region of the studied area in Wonokerto, Tirto, and Hoegeng. The average land subsidence is positively correlated with the average SPT and the accumulation of clay sediments. According to Cc, Ac, and SPT values, the marsh-swamp deposit group has the biggest impact on land subsidence with approximately depth range of -10 m to 40 m that categorized as “Very High Potential Risk”. In the end, this study offers a more secure framework for building infrastructure in regions vulnerable to land subsidence.

This study actively investigates stress ratios, principal stress orientations, and stress regimes in the West Java Province, Indonesia, by simultaneously inverting both the stress tensor and fault orientations from 232 moment tensors. It identifies diverse stress regimes, including normal and reverse faulting in the subduction zone, as well as mixed reverse and strike-slip faults across the island. Stress ratios range from 0.08 to 0.97. Sedimentary basins in the northeast produce lower values, while tectonic forces near the southern subduction zones generate higher values. In the subduction zone, plate bending generates normal faulting, while compressional forces lead to reverse faulting. The fore-arc region exhibits a variety of regimes: normal, reverse, and strike-slip, indicating transitions in the dynamics of subduction. Across the island, a combination of reverse and strike-slip faulting suggests crustal compression, with Mount Anak Krakatau exhibiting evidence of normal faulting. The study uncovers a complex interplay of subduction processes, crustal deformation, and geological heterogeneities. It outlines stress regimes ranging from normal and reverse faulting in the subduction zone to mixed reverse and strike-slip faulting on the island. These findings offer crucial insights into the tectonic processes shaping West Java, and lay the groundwork for more informed seismic hazard assessments and risk mitigation strategies.

Tsunamis are among the most terrifying natural hazards, causing significant loss of life and property and impacting our society’s human, economic, and social aspects. Given their destructive nature, developing effective techniques for tsunami observation and demolition reduction is crucial. This study proposes a novel tsunami detection and alert system utilizing fuzzy logic to mitigate these impacts. The primary objective of this research is to develop and implement a fuzzy logic-based tsunami prediction system that generates alerts indicating the likelihood of a tsunami-categorized as definite, certain, average, or rare. In the present study, we employ the fuzzy logic technique in MATLAB, using various defuzzification techniques available in the MATLAB fuzzy logic toolbox. The calculated values for the tsunami alert system in the Makran Subduction Zone are as follows: rare (1.91), average (4.75), certain (6.75), and definite (8.8). The designed tsunami alert system and model can predict tsunamis automatically and manually, potentially saving many lives more effectively than previous methods. The research objectives of this study are to (1) develop a fuzzy logic-based model for tsunami prediction, (2) implement the model using MATLAB, and (3) evaluate the model’s performance in generating accurate tsunami alerts.

Soil mineral plays an important role in agriculture due to its ability in influencing soil physical and chemical characteristics, and therefore is important to be identified. The techniques for identifying soil minerals, such as the utilization of a polarization microscope and X-Ray Diffraction (XRD), are often laborious, time-consuming, and costly. This study aims to identify and to quantify soil clay minerals by using Hyperion EO-1 imagery and XRD methods, and to reveal the effectiveness of using satellite imagery to determine soil minerals. Spectral signatures from Hyperion EO-1 were extracted in alignment with the soil sampling coordinate locations, and spectral data processing methods such as Continuum Removal (CR), and Savitzky-Golay filtering were used to identify and to quantify minerals. The results show that hyperspectral analysis revealed distinct spectral absorption features, and it could identify kaolinite, chlorite, goethite, hematite, and plagioclase. Meanwhile, XRD analysis confirmed kaolinite and chlorite, consistent with the hyperspectral observations. A key advantage of the spectral absorption technique for raw soil was its ability to identify not only clay minerals, but also both primary and secondary minerals, such as plagioclase, hematite, and goethite, that remain unidentified when using the XRD method with iron removal pre-treatment. Although hyperspectral imagery was successful in identifying soil minerals, there are still some limitations that require further refinement, especially while conducting quantification. The findings underscored the potential of satellite-based hyperspectral analysis as a rapid alternative approach to soil mineral identification that can reduce reliance on laboratory-based methods.

Khauau gold deposit, Binhvan commune, Chomoi District, Backan Province, Vietnam, is located in the Dong Bac Bo intracontinental orogenic belt. This is one of the important gold mineralization areas of Vietnam. To study the zonation of mineralization and to predict the prospect of deeply hidden buried gold ore, a research was conducted based on mineral facies analysis, fluid inclusion thermometry, ICP-MS chemistry, and morphological orebody size. The results indicate that the gold mineralization is derived from medium to medium–low temperature hydrothermal fluids associated with deep-seated formations. Inclusion homogenization temperature is from 170 to 310o C, and the main ore mineral components include pyrite, arsenopyrite to a lesser extent galena, sphalerite, and chalcopyrite. Gold mineralization-quartz-sulfur Khauau deposit is divided into three zones, which from the top to the bottom is as follows: ore zone 1 is gold-quartz-pyrite poor sulfur; ore zone 2 is gold-quartz-polymetallic; ore zone 3:is gold-quartz-arsenopyrite and pyrrhotite. Ore bodies are likely located at the depths of 125 to 540 m with many extending beyond 400 m. The depth of ore-forming processes is 562 m and the zoning coefficient of Kz= 0.83. Accordingly, it is possible to predict the prospect of the Khauau gold deposit, Binhvan commune, Chomoi District, Backan Province, to a depth of more than 500 m, and possibly extend to depths of up to 5 km.

Gosong Beach in Bengkayang, West Kalimantan, is selected as a potential Nuclear Power Plant (NPP) site candidate. Volcanic and intrusive rocks are found in the radius of 150 km from it. Based on IAEA (International Atomic Energy Agency) standard, the main assessment target is volcanic rock that is younger than 10 Ma. However, there are Tertiary volcanic and intrusive rocks next to and cover a wide area around the NPP site that show volcanic activities over the Tertiary period. Therefore, it is necessary to investigate this group of rocks to understand its characteristics. This study aims to characterize the geochemistry and petrology of the Tertiary volcanic and intrusive rocks found in northwestern Kalimantan. The fieldwork was conducted to observe and to take Serantak volcanic rocks, Bawang dacite, Niut volcanics, and Sintang intrusion samples. The XRF and micro-XRF analyses were conducted to characterize the geochemical aspect, while petrography and AMICS analyses were conducted to characterize the mineralogical aspect. The result shows that Serantak volcanic rocks, Bawang dacite, Niut volcanics, and Sintang intrusion are derived from tholeiitic to calc-alkaline as a product of mantel partial melting in the subduction zone which go through fractional crystallization. The volcanic activity was initiated by the rise of primitive parental magma from partial melting in the shallow-depth subducted crust as indicated by the garnet-free HREE pattern, the enrichment of LILE and LREE, and the depleted HREE. The Tertiary magmatism in northwestern Kalimantan was found in a small activity with a small impact on the NPP candidate site at Gosong Beach, Bangkayang.

South Sumatra region has abundant potential coal reserves, but the lack of structural and stratigraphic data makes it not be easy to map their total extent and to understand the genesis. These limitations can be partially resolved using the borehole well-logging methods. The aim of this research was to investigate correlation of coal seam lithology using the well-logging methods in a coalfield, location X, Musi Banyuasin, South Sumatra. The several exploration activities were conducted using the well-logging method to acquire gamma-ray logs and density logs data from seven boreholes, namely PMCBS12, PMCBS13, PMCBS14, PMCBS15, PMCBS16, PMCBS17, and PMCBS19 sites. WellCAD software was used during the data processing to derive logging data (gamma-ray and density logs), and Minex software was utilized to analyze the physical parameter correlation among boreholes. Borehole data analysis was carried out by analyzing the lithology contained in the borehole, especially to analyze the characteristics of the coal seam, such as depth and thickness. The results suggest that the thickness of the existing coal seam in area X is at seam 6 from a depth of about 2.95-19.95 m, with a coal seam thickness ranging from 1.85 m in the PMCBS12 to a thickness of 3.6 m in the PMCBS19 well. Two to three - vertically spread seams were found in each borehole with a thickness of about 0.35-3.6 m at various depths. Correlation results among boreholes show that the distribution of coal seams extends from the northwest to the southeast with a distribution direction of N300˚E/6˚.

The absorption of nitrogen from urea fertilizer is significantly inefficient. Due to its solubility in water. This problem can be overcome by producing slow-release fertilizer (SRF) that inhibits urea from being dissolved in water. Sulfur-coated urea (SCU) is one of the SRF methods. Therefore, this study aimed sulfur-coated slow-release urea fertilizer using sulfur waste from the Biological Sulfur Recovery Unit (BSRU) in Field X. A total of 14 tons of sulfur cake was produced daily by BSRU in Field X and sent to the laboratory for composition analysis, followed by drying. Subsequently, the dried sulfur was into a powder using a hammer and sieved to achieve a size of 200 mesh. Based on the results, SCU with the sulfur to urea ratio of 1:1 and mixing time of 15 minutes exhibited the best performance in dissolution tests with the longest dissolution time of 5 minutes which was better compared to the uncoated urea. After 7 days of observation, spinach that received SCU was more fertile and greener. The calculated NPV and payout time were 88712 million IDR and 1.76 years, respectively. This indicated that the development of this study was economically attractive. In conclusion, the value of sulfur waste from gas processing was increased by using sulfur waste from BSRU as a coating of urea while reducing related environmental effects.

An integrated study of several methods to characterize a carbonate reservoir provides a comprehensive result on carbonate facies and diagenesis. Therefore, a study on the Tertiary carbonate reservoir at the East Arm of Sulawesi area, Banggai – Sula Basin, is intended to determine the Salodik Group carbonate reservoir facies and diagenesis. Moreover, the purpose of this study is to determine the intensity and implication of syn-depositional or post-depositional processes, and to provide the reservoir final properties values, such as porosity and permeability to classify the reservoir quality. The methods of the study are based on carbonate fieldwork mapping to obtain samples on distributed traverses. Further analyses are the laboratory works to determine facies and diagenesis features on a more detailed scale. This study shows several facies, dominantly classified into reefal packstone, planktonic foraminifera packstone-wackestone, large foram packstone-mudstone, skeletal packstone-wackestone, planktonic-large foraminifera packstone-wackestone, and large foraminifera-red algae packstone. The dominant diagenesis processes are cementation and dissolution. Moreover, meteoric vadose and meteoric phreatic are predominantly the main diagenesis environment of Salodik Group formations. Furthermore, the dominant diagenesis stage is Eogenetic. The post-depositional process or the diagenetic processes, provides a more significant impact on carbonate reservoir properties than the syn-depositional process as shown on lithofacies texture. However, in general, from the younger to the oldest formation of Salodik Group, this shows a decreasing trend of reservoir properties due to the dominantcementation process in the oldest formation. Overall, the reservoir quality referring to porosity value is classified as negligible to excellent. While, based on permeability data, it is classified as the tight to good reservoir.

The northern part of Pemalang City consists of Quaternary deposits, having the potential for earthquake amplification effect. This amplification effect amplifies the ground shaking because of an earthquake (the local site effect) that has the potential to cause damage. This study investigated the amplification factor from the HVSR curve of microtremor measurements due to soil response based on ground shear strain, the risk level of the earthquake based on peak ground acceleration (PGA), and earthquake intensity. The microtremor data from five locations in Pemalang were used to calculate the amplification factor and predominant frequency. The damaging earthquake parameters around Java during 2010-2020 were used to calculate the PGA. The microtremor data were processed using the HVSR method, and PGA was calculated using the Kanai equation. The HVSR result shows that Pemalang has an amplification factor ranging from 6.23 to 19.59 and ground shear strain varying between 0.86 x 10-4 and 6.67 x 10-4, which shows that Pemalang only experiences the vibration when an earthquake occurs. The PGA results using the Kanai equation (19.71-54.56 gal) were included in the low vulnerability category, and MMI earthquake intensity (3.08-4.70) was included in the felt earthquake category (II SIG BMKG scale). Therefore, the amplification factor from the HVSR curve of microtremor measurement, ranging from 6.23 to 19.59, showed low soil response and low-risk vulnerability based on the damaging earthquake parameter around Java during 2010-2020. Keywords: peak ground acceleration, amplification, microtremor, PGA