This study presents a comprehensive geochemical and hydrogeological characterization of the Wayang Windu Geothermal System in West Java, Indonesia. The research aims to identify water and gas chemistry patterns, to determine fluid origins, and to estimate reservoir temperatures to support conceptual modeling of the geothermal field. Field sampling was conducted on hot and cold springs and fumarolic gases, complemented by laboratory analyses of major ions (Cl⁻, SO42⁻, HCO3⁻; Na⁺, K⁺, Mg2+), stable isotopes (δ2H, δ18O), and gas compositions (CO2, N2, Ar). Data interpretation employed standard geochemical tools, including Cl-SO4-HCO3 and Na-K-Mg diagrams for water classification, δ2H-δ18O plots for recharge source identification, and N2-CO2-Ar ternary diagrams for gas origin assessment. The results indicate that sulphate-type hot springs mark upflow zones, while bicarbonate-type warm and cold springs reflect lateral outflow and mixing processes. The isotopic signatures confirm predominantly meteoric recharge with localized steam-heated and magmatic influences. The gas geothermometers estimate reservoir temperatures between 225° and 286° C, and Cl-Li-B relationships reveal three distinct reservoir clusters: Gambung, Wayang, and Windu. These findings provide critical insights into fluid pathways, reservoir structure, and recharge dynamics, forming a robust basis for sustainable geothermal resource management in volcanic settings.
work improves seismic hazard evaluation for the Lampung region in Sumatra by tackling the precision in magnitude conversion, attenuation of seismicity, and area-source modelling. Considering the variety magnitude. The magnitude conversion equations were initially validated using scales from historical earthquake data. And, if required, enhanced to guarantee their dependability for the area. Utilizing maximum likelihood estimation Maximum Likelihood Estimation (MLE) and ordinary. Ordinary least squares (OLS) regression was employed to compute parameters for frequency-magnitude distributions. Facilitating a comprehensive comparison that acknowledges OLS's sporadically superior alignment with observed data. Gaussian distribution smoothing was utilized diverse bandwidths (25, 50, 75, and 100 km) to illustrate spatial seismicity patterns, disclosing a distance of 50 kilometers. Bandwidth provides the most consistent model performance, especially in terms of accuracy in the Molchan illustration. The area skill score (ASS) validates the superior forecasting capacity of the smoothed seismicity models. Using bandwidths of 25, 50, and 75 kilometers producing competitive outcomes. Furthermore, the region was partitioned into discrete seismic zones predicated on fault characteristics and seismicity density, further augmenting localized hazard assessments. This is polished. multi-method approach encompassing magnitude conversion, spatial smoothing, and area-specific analysis. Modelling offers a comprehensive framework for seismic hazard preparedness in Lampung, providing useful insights for infrastructure strategic planning and disaster mitigation.
Modeling the Earth's subsurface is important in geophysics, for example, tomography and Full Waveform Inversion (FWI). Especially for FWI, it is a method in the geophysical field that is used to describe the subsurface with a high-resolution image by utilizing all parts of observation data (seismic traces) based on a velocity model. In this paper, the 3D synthetic geological modelling was generated as an initial model; then, based on it, seismic traces and also shot gathers were simulated by arranging sources and geophones, and finally, the FWI was done. After seismic traces (assumed as acoustic wave equations), complete with the smoothness, were obtained, then a hyperbolic partial differential equation between the time and space domains was applied before entering the inversion process. During the inversion process, the final seismic traces were obtained by velocity updating in the entire space and time until they reached zero misfit, so wave propagation and the final velocity model could be observed. The pattern changes of seismic traces, shot gather, wave propagation, and FWI could be described by modifying the seismic source and geophone location in the geological model. However, by generating a 3D synthetic geological model, there is much flexibility for getting various descriptions of acoustic wave simulations.
site suitability for utilizing sand deposited land is an important step towards sustainable development by adopting conservative measures. Soil is the most crucial for maintaining an environment and ecosystem which is helpful to sustaining all forms of life. The increasing action of sand deposition day to day has been one of the common issues all over the world, especially the country with high magnitude flood. The present study aim is to identify the sensitive area of the sand deposition within The Dibru River Basin. Multicriteria evaluation is carried out using Geographic Information System (GIS) techniques to help the choice makers in identifying the suitable site of sand deposition. Different layers which were considered for multicriteria evaluation are: sand deposition, geomorphology, soil capability, soil texture, and slope for identifying the vulnerable zone of sand deposition. Analytical Hierarchy Processes (AHP) are used for weighted sum to find the sensitive area of the sand deposition for land management using selected criteria. The site suitability map was classified into low, moderate, and high deposition zones. This paper will help policy makers for implementing the preventive measures to use the siltation zone into sustainable within The Dibru River Basin.
Underground coal gasification (UCG) is a clean coal technology that converts coal in-situ into synthetic gas (syngas) through thermal and chemical reactions. Coal pyrolysis, a key reaction in UCG, initiates the thermal decomposition of coal, and influences gas yield and composition. This study examines the influences of pyrolysis temperature and coal rank on gas production using coal samples from The Muara Enim Formation, South Sumatra Basin. Four coal samples, ranging from lignite to bituminous rank, were pyrolyzed at 300, 400, 500, and 600 degrees C under inert conditions. The results indicate that gas yield increases with temperature due to enhanced thermal decomposition. At lower temperatures (300-400 degrees C) CO2 dominates, particularly in lower-rank coals due to their higher oxygen content. At higher temperatures (500-600 degrees C) more CH4 and H2 productions become more prominent, particularly in higher-rank coals. CH4 generation is driven by the breakdown of aliphatic structures, while H2 production results from dehydrogenation and condensation of aromatic structures. Lower-rank coal produced higher gas at low temperatures, indicating greater suitability for UCG under such conditions. In contrast, higher-rank coals require elevated temperatures for effective decomposition due to their greater thermal stability. These findings provide valuable geochemical insights into the pyrolysis behaviour of Muara Enim coals and offer a scientific basis for optimizing UCG conditions to improve gas yield and quality.
Hippopotamidae are known to have lived in the island of Java based on the presence of their fossils. Several researchers have described and concluded that there are three species of Hippopotamidae in the island of Java, but there are also those who argue that the three types of Hippopotamidae are of the same species. These differences give rise to further discussion regarding what species lived in the island of Java in the past. Twenty Hippopotamidae fossil specimens including twelve specimens recently discovered, and previously undescribed specimens collected form stratigraphic context from Java were analyzed in this study and compared with previous literature. This study of Hippopotamidae fossils is based on skulls and teeth where the number of incisor teeth is one of the distinguishing characters which shows that all Hippopotamidae fossils in Java Island are from the genus Hexaprotodon. Our evidence shows that there are two types of Hexaprotodon in Java, namely the relatively small Hexaprotodon in The Gelasian-Calabrian-Chibanian Pleistocene, and a larger Hexaprotodon of Late Chibanian-Late Pleistocene age. Based on its anatomy, the small Hexaprotodon from Java is called Hexaprotodon sivajavanicus, while the large Hexaprotodon from Java is called Hexaprotodon megakendengensis
The research location is in the Kulon Progo Mountains, west of the Daerah Istimewa Yogyakarta province and part of Central Java. Several previous researchers have discussed the stratigraphy of the Kulon Progo Mountains region, following the rock unit grouping rules that have evolved from the past to the present. Approaches to clarify the geological conditions of the Kulon Progo Mountains and efforts to comply with Indonesian Stratigraphic Code standards are continuously being carried out. The purpose of this study is to identify volcanic stratigraphic units in the Kulon Progo Mountains using the principles and concepts of volcanic stratigraphy. The research methods used were surface geology research and remote sensing. The research conducted through surveys or field visits at specific locations was identified as key areas of interest. Remote sensing and topographic map analysis were also conducted to delineate the distribution of volcanic rocks and the boundaries of volcanic stratigraphic units. Laboratory analysis was conducted to strengthen the interpretation of volcanic rock genesis and thus support the interpretation of the presence of volcanoes in the study area. Comprehensive analysis is used to determine the location of ancient eruption sources, descriptions of coherent and pyroclastic lava, and the origin of volcanoes, which have developed quite significantly, as well as the volcanic stratigraphic units in the study area. The volcanic stratigraphic units of the Kulon Progo Mountains from the early to late activity periods are grouped into the Gajah Brigade, Ijo Brigade, and Menoreh Brigade stratigraphic units. The collection of volcanic stratigraphic units from the three brigades that built the Kulon Progo Mountains and were mapped at a scale of 1:100,000 is called Super Brigade Kulon Progo. The Gajah Brigade Unit is in the center, the Ijo Brigade Unit is in the south, and the Menoreh Brigade Unit occupies the northern part of Super Brigade Kulon Progo, which is in a relatively northeast-southwest trend. The Gajah Brigade covers the north side of Crown Bujel, which is bounded by a long escarpment that opens to the west, and the flat Crown Pencu is bounded by a curved escarpment that also opens to the west. Ijo Brigade is in the southern part of the Kulon Progo Mountains and has a relatively rounded shape, bounded by steep escarpments, especially on the north and east sides. The geological elements of the ancient volcano Ijo Brigade appear much clearer than those of the other brigade, so it is estimated that it is younger than the time the Gajah Brigade was formed. Ijo Brigade covers two ancient volcanic bodies, namely Ijo Crown in the north and Kukusan Crown in the south. Menoreh Brigade is in the northern part of the Kulon Progo Mountains and is the youngest of the three brigades that built Super Brigade Kulon Progo. The Menoreh Brigade encompasses the Gupit Crown, which is a dacite intrusive body, the smallest in diameter and the lowest in topography among the existing Crowns. The stratigraphy of the ancient volcanoes of the Kulon Progo Mountains is arranged by volcanic unit levels from large to small, namely Super Brigade, Brigade, and Crown.
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.
assessment of heavy metal contamination is pivotal in understanding environmental health and its impacts on aquatic ecosystems. This study aims to assess the concentration and distribution of heavy metals in the sediments of The Paradgaon Lake (PL) of Umrer Taluka, Maharashtra State, India, and to evaluate the level of pollution and ecological risks using various pollution indices. Six surface sediment samples (three each during pre and post monsoon seasons) along with five soil samples were collected from the PL and surrounding locations, respectively in the catchment of the PL. The air-dried powdered sediment samples were analyzed for the heavy metal concentrations using X-Ray Fluroscence (XRF) Spectrometry. The present study investigates the contamination of the heavy metals such as iron (Fe), aluminium (Al), manganese (Mn), zinc (Zn), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), cobalt (Co), uranium (U), vanidium (V), and rubidium (Rb). The appraisal of sediment contamination was analyzed on the basis of enrichment factor (EF), Geo-accumulation Index (GI), Contamination Factor (CF), and Pollution Load Index (PLI). Additionally, ecological risk factor (Er) and potential ecological risk index (PERI) were calculated to comprehend the toxicity of heavy metals and the environmental response to all risk factors. The key metal contaminants in lake surface sediments include Fe, Al, Zn, Mn, Cr and Co. This study demonstrates that these heavy metals were generated from the common lithogenic source generated through weathering and erosion of the Deccan Trap Basalt (DTB) and associated soils in the catchment in addition to partial input from the adjoining coal mining. The heavy metals such as Zn, Cu, Cr, Ni, Pb, U, and Rb showed their higher concentrations during the premonsoon (PM) season as compared to the postmonsoon (PoM), while metals like Al, Fe, Mn, Co, and V have increased concentrations during the PoM season, indicating enhanced weathering and erosion in the different parts of the rocks (DTB) and associated soils contributing these metals during the monsoonal season in the catchment of the PL. The geoaccumulation index and contamination factor of the heavy metals in the PL showed moderate pollution level. These metals may be originated from anthropogenic sources such as agricultural runoff and coal mining in addition to natural geological processes. Overall, the study on Igeo, CF reflects moderate level of pollution, whereas the EF and Er clearly signifies the changes in land-use type and rainfall patterns on heavy metal accumulation in the present lake. The strong positive correlation between Mn and total organic carbon (TOC) points their biogenic source, while Pb has high positive correlation with total inorganic carbon (TIC) and moderately correlated with TOC indicating mainly anthropogenic origin of Pb with its input from coal mine and deposited in the soils of the catchment of the PL. The present findings also provide valuable insights of the environmental risk of heavy metals pollution in the Paradgaon Lake.
Porosity estimation of gas reservoir rocks is a crucial challenge for many oil fields, which may drive to the uncertainty of reserve assessment. However, wirelines are normally available, and considered a neat source of porosity measurement, where logs and core samples are two sources of direct and indirect rock porosity data. The main objective of this paper is to demonstrate the impact of the porosity logs on the water saturation (Sw) assessment of the gas-bearing F3 sandstone reservoir (Aouinet Uennin Formation, Devonian). This geologic formation represents a giant reservoir of the Al Wafa Gas and Oil Field, Ghadames Basin (Libya). The studied reservoir (Devonian) is a clean gas-bearing sandstone reservoir that has a shale content of less than 25 %, which may be considered a potassium feldspar sandstone rock type. Besides, different log categories of the porosity-total porosity (phi nd), neutron porosity (phi n), and sonic porosity (phi s) illustrate high values of the water saturation (Sw) estimation due to the gas appearance. Whereas the density porosity (phi d) yields the lowest values of the Sw. Moreover, the Id demonstrates a high agreement with the core porosity (phi core), which verifies less uncertainty of the petrophysical assessment in the F3 Sandstone gas-bearing reservoir.
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.
The earthquake hazard must be mitigated at the prospective nuclear power plant site in Serpong, Tangerang, to avoid damage to the nuclear installation infrastructure, especially the possibility of liquefaction. This study combines Probabilistic Seismic Hazard Analysis (PSHA) with Ground Motion Prediction Equation (GMPE) (Abrahamson, 2014), which is used as a probabilistic prediction model. This is to estimate spectral accelerations and Peak Ground Acceleration (PGA) based on earthquake magnitude, distance, and site characteristics. Calculations were carried out using OpenQuake for PHA calculation and Seismomatch for spectra matching analysis, which produced the deaggregation results used to define the target spectrum. Representative time histories were chosen using the SMART technique, which uses ranking and weighting to assure compliance with deaggregated magnitude-distance situations, then refined using spectral matching of 90 records while keeping nonstationary properties. Both shallow crustal and subduction events have a substantial impact on seismic demand, with the 2011 Tohoku earthquake (Mw 9.0, depth 29 km, distance 245.9 km, PGA 0.26 g) appearing as the most compatible scenario and primary contributor to possible site risks. The suggested paradigm provides a realistic solution to site-specific ground motion selection and liquefaction risk assessment, hence promoting nuclear safety and seismic resilience in tectonically active regions.
- The sustainable utilization of geothermal resources heavily relies on maintaining the fluid mass balance within the reservoir. Excessive fluid extraction without sufficient natural recharge can cause significant declines in reservoir pressure, thus threatening the long-term sustainability of geothermal energy production. This study specifically addresses the challenge of accurately characterizing natural recharge dynamics in the Lahendong Geothermal Field, where ongoing exploitation activities have led to considerable fluid mass deficits. To tackle this issue, time-lapse microgravity monitoring was conducted annually from 2015 to 2023 across 118 gravity benchmark stations strategically distributed throughout the reservoir area. The collected microgravity data were analyzed using Gauss's theorem to quantify the changes in reservoir mass balance over time. The calculated reservoir mass changes based on microgravity data were validated against mass balance estimates derived from actual well flow rate measurements. The findings indicate that natural recharge in Lahendong varies significantly, ranging from 0 to 3 M ton/year, exhibiting a clear cyclical pattern with approximately three-year intervals. On the average, natural recharge supplies approximately 1 M ton/year to the reservoir. The results validate time-lapse microgravity monitoring as a robust tool for detecting reservoir mass changes, offering critical insights into adaptive fluid injection strategies.
The southern coast of Trenggalek District is prone to tsunami disasters, because it is located north of the megathrust zone. This study aims to map the level of tsunami inundation risk in The Trenggalek District, especially on the coast of Watulimo Subdistrict. This mapping was done with the help of Model Builder in ArcGIS software, using scenarios of tsunami wave heights on the shore of 1 m, 2 m, 5 m, 15 m, 27 m, and 30 m. The risk map of tsunami inundation was obtained by combining the tsunami hazard map with the vulnerability map. The study results show that the area of tsunami inundation at a high-altitude scenario with wave heights of 1 m has low, medium, and highrisk levels covering 0.254 km(2), 0.240 km(2), and 0.032 km(2), respectively. In the 27 m scenario, which is the worst-case scenario according to Meteorology, Climatology, and Geophysics Agency (BMKG), the areas of inundation at low, medium, and high-risk levels reach 23.032 km(2), 16.471 km(2), and 7.904 km(2), respectively. In this 27 m scenario, four villages in Watulimo Subdistrict are almost entirely inundated by the tsunami. The results of this study are expected to be used as the material for tsunami disaster mitigation in the Trenggalek District.
- Indonesia has many cases of volcanic debris avalanche (VDA), which is fifty-four events from the inventory conducted by MacLeod (1989). However, data on the characteristics of VDA provided is limited, therefore it is necessary to develop detailed information related to these fifty-four cases. This study focuses on morphological and geological inventory of the VDA in Indonesia. Using the DEM database, morphological features were analyzed and four classes were determined, namely (1) volcanoes with horseshoe-shaped scar only; (2) volcanoes with no horseshoeshaped scar, but has DAD (debris avalanche deposit); (3) volcanoes with no horseshoe-shaped scar, and no DAD; and (4) volcanoes with horseshoe-shaped scar and with DAD. Most of the volcanoes that have VDA are clustered in the first class. From the geological map, three main main pieces of information can be obtained: relative age, rocks/ materials, and structure. Of fifty-four reported VDA events, the age of the rocks build the volcano that commonly ranges the Pliocene, Pleistocene, and Holocene. The composition material is relatively uniform, consisting of lava with basalt-andesite rock types. Scar structures are also delineated in some volcanoes. Based on these characterization results, its relationship with volcano types in Indonesia (e.g. type A, B, C) was analyzed to determine the potential for reoccurrence of VDA. Further analysis is proposed, along with a more comprehensive characterization of the VDA in Indonesia, particularly at the type A volcanoes, such as Dempo, Galunggung, Gede, Papandayan, Sundoro, and Raung.
Mafic alkaline igneous rocks, along with their weathering products, are a significant source of Rare Earth Elements (REEs) and critical elements. One of the mafic alkaline rock-related REE and critical element sources is lamproite. Various methods were utilized in this study, including optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy with Energy Dispersive Spectroscopy (SEM-EDS), as well as whole-rock geochemical analyses using X-ray fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry/Optical Emission Spectroscopy (ICP-MS/OES). Based on mineralogical observations, it has been confirmed that the dykes from West Sulawesi are orendite-type lamproite rocks. Sanidine, phlogopite, diopside, and aegirine are the main minerals found in these rocks, including apatite and oxide minerals as accessory minerals. The dykes' whole-rock geochemistry indicates an ultrapotassic nature with a K2O/Na2O ratio > 3. Lamproite dykes display an increase in the large ion lithophile elements (LILEs) and a decrease in Ti, Sr, and P, with minimal Eu anomalies. They also show an increase in the light rare earth elements (LREEs), ranging from 901 to 1558 ppm, and a significantly higher content of Zr (968-3083 ppm), Th (152-408 ppm), and U (30-37 ppm). The dykes are related to an orogenic lamproite that formed during post-collisional tectonic continental extension. It contained a significant amount of REE-Zr-Th-bearing minerals, such as apatite (La-Ce-Nd), zirconosilicate (Zr-Ce), and Ba-perovskite (Zr-Th-Ce-Tb). The enrichment of light rare earth elements (LREEs), thorium (Th), and zirconium (Zr) in these dykes can be attributed to both primary and secondary enrichment processes, such as metasomatism and hydrothermal alteration. This phenomenon is evidenced by mineral replacement textures or pseudomorphs, as well as a skeletal texture resulting from rapid cooling in a hydrothermal fluid environment. Therefore, understanding the formation of mafic alkaline rocks, especially lamproite, and their role in enriching REEs and critical elements is a crucial future scientific goal.
Geochemical fingerprints offer useful insight into source inputs, thermal maturity, and alteration processes. Nonetheless, detailed light hydrocarbon (LH) compositional studies across The Niger Delta have not adequately been considered. Thus, twenty-six oil sets from several subbasins (depobelts) were examined, using gas chromatography (GC) approach, aimed at determining the source input and thermal maturity in-reservoir alterations, and then correlating the oils. This provides critical insights for oil characterization in the basin by examining the distribution and abundance of LHs. Mango's invariant K1 ratio of LHs clearly delineates the oils into two homologous sets, with a narrow range (0.83 ̶ 0.94 and 0.95 ̶ 1.13), consistent with the plot of ph/nC18 vs. pr/nC17 of heavy molecular weight (HMW). The studied oils reflect a modest distribution between Thompson's aliphatic and aromatic curves scheme (Kerogen Type), with heptane ratios varying from 0.64 to 22.04 %, on the average of 16.19 %, indicating contributions from a range of sources typical of type II/III kerogen. The LHs component of the examined oils has an overall six-ring preference, with methylcyclohexane varying from 46.15 to 81.86 %, the average of 56.50 %, dimethyl-cyc %, suggesting a significant input from higher plants. The data suggest expulsions from various source rocks of terrestrial organofacies, with variable contributions from marine sources that were initially laid down in oxic to sub-oxic environments, and range from early to peak oil thermal maturity. Nonetheless, most samples from Greater Ughelli showed varying degrees of evaporative fractionation, suggesting gas washing in the depobelt.
This paper examines the phenomenon land subsidence occurring in Kendal-Semarang, on the northern coast of Central Java Province (Java Island, Indonesia). Previous studies suggested that anthropogenic processes, particularly the over-exploration of groundwater, caused land subsidence in Kendal City and northern Semarang City. However, the geological factors such as sedimentology and stratigraphy below the Holocene deposit are possibly contributing to land subsidence in the Kendal-Semarang area remain unclear. This paper aims to analyze the stratigraphy, sedimentology, and insight into compaction and land subsidence potential of the basement Kendal-Semarang region within the Pliocene-Pleistocene Upper Damar Formation, based on measured sections in selected areas, analysis of deep pile benchmarks, and geotechnical aspects by using Standard Penetration Test (SPT) analysis. Specifically, it investigates the relationship between sediment loading and recent geological changes, related natural phenomena, erosion, and sedimentation, that may influence land stability. Detailed stratigraphic analyses were conducted in six selected locations through field measurements and borehole data to achieve this. These data were complemented by foraminifera and pollen analyses used to date the formation accurately. The stratigraphic interpretation suggests that during the Middle to Late Pliocene, the deposition environment of the Damar Formation transitioned from an upper delta plain to a tidal-influenced pro-delta environment. Two deep-pile benchmarks were also installed to monitor land movement, which revealed significant subsidence over one month, with rates of approximately 2.4 to 2.9 millim per month. These findings are supported by Standard Penetration Test (SPT) results, indicating that the underlying black and grey clay of the Upper Damar Formation-serving as the basement rock-exhibits N-SPT values between 5 and 27, ranging from firm to very stiff. Additionally, SEM analysis showed the prevalence of illite-smectite clay minerals, suggesting a moderate to high potential for compression and settlement under wet conditions. Understanding the compaction behaviour of these sediments helps explain ongoing land subsidence issues in the region, which is crucial for land use planning, infrastructure development, and hazard mitigation.
The Proterozoic volcanic and metasedimentary sequences of Kirana Hills, Punjab, Pakistan, provide critical insights into the region geodynamic evolution of the northwestern margin of The Indian Shield. This study investigates the region stratigraphy, structural framework, and lithological variations of The Kirana Complex, and analyzes fracture studies to reconstruct regional geodynamic processes. The aim of this research is placed on understanding how volcanic and metasedimentary assemblages, along with deformation patterns, reflect the tectonic settings and subsequent crustal evolution of the area dated back to approximately 870 ± 40 million years. The studied region field investigations, geological mapping, and fracture analyses were combined with factor-mapped datasets. Fracture characterization was performed using circle inventory methods for the three sites to quantify structural orientation, density, porosity, and permeability. The rose diagram interpretation for the fracture analysis study was performed using permeability, and using the circle inventory method to understand tectonic deformation and fluid movement. The findings suggest that the region is exposed to Proterozoic sequences of volcanic rocks dominated mostly by rhyolite, basalt, dolerite, quartzite, and volcanogenic slates of mostly Hachi Volcanics and Mach Super Group with distinct evidence of multiple magmatic and tectono-metamorphic phases. Field evidence of felsic-mafic associations, mineralization (hematite, limonite, micaceous hematite, jasper, and bornite), and other alterations highlight fluid-rock interaction and multiple shifts of mineralization. The fracture studies show (i). Hadda Quartzite shows N-S oriented conjugate fractures associated with compressive stress and migration of paleo-fluids; (ii). In the Buland Hill Formation, there is evidence of radial and concentric fractures around volcanic vents with mineralized joints that indicate signs of hydrothermal activity; and (iii). The Foliation-aligned fractures of The Asianwala Formation suggest the related foliation-based shear deformation. Taken together, these characteristics point to the existence of an initial history of extensional regimes associated with continental rifting, then compressional reworking and progressive deformation. This work lies in its integration of fracture analysis study with regional structural and lithological studies and mapping of site characterization during the field analysis. This approach refines existing models of Kirana by linking fracture-controlled fluid migration to broader geodynamic processes.
The 2024 eruptions of Ruang Volcano in North Sulawesi, Indonesia, represent one of the most explosive and impactful volcanic events in the region's recent history. The eruption sequence, which commenced on April 16th and peaked with significant explosive episodes on April 17th and 30th, resulted in the evacuation of over 9,000 residents and demonstrated the volcano’s capacity for high-energy eruptive activity. This preliminary analysis of the April 30, 2024, Ruang Volcano eruption emphasises the importance of ejected materials—such as high-vesicular juvenile fragments, crystal-rich components, and megacrysts of amphibole (hornblende)—in revealing the eruption’s explosive signature. Geochemical analysis of juvenile materials indicates a basaltic andesite composition, with SiO₂ contents ranging from 53.02% to 54.27%. Petrographic examination and SEM observations reveal high vesicularity, ruptured bubble walls, and microlite-rich groundmass textures, indicative of rapid ascent and intense degassing, which facilitated efficient magma fragmentation. These features suggest that the magma underwent rapid decompression. Understanding these properties provides important clues about the mechanisms underlying the explosiveness of the Ruang eruption.
