Table of contents

International Conference on Geological Engineering and Geosciences

ICGoES 2021

International Conference on Geological Engineering and Geosciences (ICGoES 2021) presents 'Big City Challenges on Geohazard and Georesources' as the main conference theme. This conference provides a forum for international researchers, academics, practitioners, policymakers and related communities to discuss, share and exchange their latest research and experience progress associated with the field of geological engineering and geosciences. In addition, this conference also aimed to address a common issue of georesources sustainability, renewable energy sources and climate change-related geohazard and disasters in the development of urban areas. Certainly, those issues require an integrated approach and collaborative efforts in particular to build and enhance resilient cities in the respective countries.

ICGoES 2021 provides opportunities to all participants in expanding their network, as an important step to achieve a coordinated approach and interdisciplinary collaboration at the regional and international level in the field of geological engineering and geosciences. We invited research papers on the topic of geohazard and georesources; but not limited to research papers, recent cases, and in-depth reviews of basic geology, applied geology, geophysics, geochemistry, engineering geology, geo-environmental engineering and any related geoscience.

Due to the COVID-19 pandemic situation during the year, it is not easy to hold a regular conference in a specific place. There were travel restrictions and regulations from the World Health Organization and the Indonesian Government to be complied with to cut the spread of the COVID-19 virus in terms of physical distancing. In this uncertain condition, the ICGoES should not be postponed since participants have arranged to address their research findings at this conference. Thus, the committees of ICGoES have decided to switch the conference format into a virtual meeting using ZOOM.

List of Committees, Conference Photos are available in this pdf.

All papers published in this volume of IOP Conference Series: Earth and Environmental Science have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

• Type of peer review: Double-blind

• Conference submission management system:

Full paper submission was fully managed through EasyChair that can be accessed at https://easychair.org/conferences/?conf=icgoes2021. All required information of the conference can be accessed at https://icgoes.geologi.ugm.ac.id/

• Number of submissions received: 73 full papers

• Number of submissions sent for review: 73 full papers

• Number of submissions accepted: 52 full papers

• Acceptance Rate (Number of Submissions Accepted/Number of Submissions Received X 100): 71.23 %

• Average number of reviews per paper: 2 reviewers

• Total number of reviewers involved: 53 reviewers in total from 10 countries

• Any additional info on review process:

The review process and revision were conducted 2 rounds on average for each paper since the first submission before the conference until the final decision after presentation at the conference. The third-round of review was required only for papers that need major modifications. All reviewers were asked to complete the review within enough time ranged between 10-14 days. While authors were asked to revise according to suggestions by reviewers within time ranged between 10-14 days. After being accepted, English proofread and similarity checking via Turnitin were carried out to ensure the quality prior to submission to IOP EES. About 90.38% (46 papers) of 52 total accepted papers have the similarity of less than or equal to 15 %. Papers with a similarity index exceed 20% were rejected.

• Contact person for queries:

Name: Hendy Setiawan, Ph.D.

Affiliation: Universitas Gadjah Mada, Faculty of Engineering, Department of Geological Engineering

Email : hendy.setiawan@ugm.ac.id

Based on historical records, Yogyakarta has a high seismic risk related to the earthquake events along active faults, such as the Opak and Merapi-Merbabu Faults. These faults were responsible for several destructive earthquakes in Yogyakarta City and its vicinity and caused fatalities and building damage in the area, e.g., the 2006 (Mw 6.3) Yogyakarta earthquake and earlier in 1943 and 1867. A previous study shows that the Opak Fault has a geodetic slip-rate of 5 mm/y and a potential magnitude Mw 6.6. In addition, the active Merapi-Merbabu Fault has a geodetic slip-rate of 1 mm/y and a potential magnitude Mw 6.6. We used scaling law relations of earthquake parameters and magnitude scenarios to estimate the recurrence time of each fault based on a kinematic model. Our results estimate that the earthquake return period (Tr) for the Opak Fault (Mw 6.6) is ∼162 years, the maximum intensity is ∼VII-VIII MMI scale, the Peak Ground Acceleration (PGA) is ∼36 % g, and Peak Ground Velocity (PGV) is ∼ 30 cm/s for a 5 km hypocentral depth. In the meantime, the earthquake return period for the Merapi-Merbabu Fault (Mw 6.6) is estimated to be ∼810 years, the maximum intensity is ∼ VI-VII MMI, the PGA is ∼ 30-36 % g, and the PGV is ∼ 21-24 cm/s for a 5 km hypocentre depth. Both faults potentially produce destructive earthquakes (Mw > 6.0) in Yogyakarta City and its vicinity. Therefore, assessments of (paleo) earthquakes are needed of both the Opak Fault and the Merapi-Merbabu Fault to support the long-term earthquake hazard mitigation program.

The review of the seismogenic zone characteristics associated with the earthquake rupture process in the Sumatra Subduction Zone has been carried out by various methods. This zone has experienced several major earthquakes; Aceh 2004 Mw=9,1, Nias-Simeulue 2005 Mw=8,6, Bengkulu 2007 Mw=8,5, and Enggano 2000 Mw=7,9. This study focuses on the relationship between density contrast analysis based on gravity data from the GOCE satellite and the slip distribution in four major earthquake rupture zones. Satellite gravity data processing is carried out to obtain data for Gravity disturbance (Gd) and vertical gravity derivatives (Tzz), corrected by topography and sediment effects with different spectrum decomposition to get gravity maps with different depths. Based on the Tzz analysis, the maximum slip of the earthquake rupture is correlated with the minimum Tzz pattern and low-density contrast. In contrast, the rupture ends at the maximum Tzz pattern and high-density contrast. Tzz pattern and Gravity disturbance can describe the barrier and asperity of the Sumatra subduction zone. The schematic maps portray the seismic segmentation of Sumatra Subduction, which have asperities zone along the subduction strike associated with the minimum Tzz and associated with the forearc zone, as well as the barrier related to the maximum Tzz, which is a manifestation of structures (fracture zone and seamount) that are subducted to the oceanic plate.

Magnetotelluric (MT) research was conducted to map the fault structure in the western part of East Java. The advantage of the magnetotelluric method is its deep penetration because it propagates at a low frequency so that it can detect resistivity anomalies that are thought to be faults. The measuring path of the magnetotelluric method covered the Surabaya and Gresik areas. Research conducted in densely populated areas thus it requires a noise reduction process to improve the quality of the data. Performing the robust processing with Rho Variance parameters and editing XPR is an effort to reduce noise and to improve the quality of magnetotelluric data. The robust processing result of 5 (five) sounding MT data using the Rho Variance parameter can improve the quality of magnetotelluric data by increasing the coherence value of 2.128% (MT01), 2.804% (MT02), 2.378% (MT03), 3.508% (MT04), and 3.129% (MT12). Meanwhile, the editing XPR process can increase the coherence value of 0.184% (MT01), 7.155% (MT02), 9,364% (MT03), 0.784% (MT04), and 0.628% (MT12). Escalation of coherence value by implemented the Rho Variance and Editing XPR means that two methods are sufficient effectively to raise the confidence level of MT data processing and interpretation result.

Halmahera is an area with active tectonics, so it has a high level of seismicity. Swarm earthquakes occurred in Jailolo from November to December 2015, and then in 2017, another earthquake swarm occurred from September to October. This earthquake is characterized by an increase in the number of earthquakes in a certain period with a relatively small magnitude, without mainshocks, and occurs in volcanic areas. This research used arrival time from P and S waves recorded at Taide Digital Seismograph (TDS) which was positioned at Ternate Geophysical Station (TNTI). We used cross-section on hypocenter to see the depth distribution using GMT and determination of b-value using ZMAP code. From the results of this study, the variation in the magnitude of the earthquake swarm obtained ranged from 0.7 to 5.0 with a depth of 7.7-12 km. Our results show a b-value of aproximately 1.0 in the area near Jailolo Volcano, 1.0-1.5 in the northwest of Jailolo and 1.0-2.0 in the southeastern part of Jailolo. Based on b-value we obtained, the characteristics of the Jailolo swarm earthquake tend to be influenced by magmatic activity.

Throughout the island of Java, several shallow faults located in the vicinity of densely populated areas accommodate the tectonic strain generated by the subduction of the Indo-Australian Plate beneath the Sunda Plate. These faults are characterized by a poor surface geomorphological expression due to the tropical climate that masks paleoseismological evidence making the identification of active faults in this environment challenging. We present preliminary data of a tectonic-geomorphic study that aims to identify and characterize active faults in the province of Yogyakarta (Central Java) as a basis to improve seismic hazard assessment. Here we focus on the Opak fault by describing its geomorphology and structure, using field data and remote sensing-based observations to contribute to the understanding of its geometry, kinematics, and tectonic activity. We show preliminary data supporting the Opak Fault as an active SW-NE transtensional left-lateral strike-slip reactivated normal fault consisting of several parallel fault strands. Although geomorphological expression of active tectonics is poor and diffuse, we found numerous field evidence of active tectonics ranging from tilted Quaternary fluvial terrace risers, triangular facets, and linear valleys to peculiar drainage patterns that allow us to provide evidence of the Holocene activity of the Opak Fault.

Indonesia is a country located at the meeting of three tectonic plates. This condition makes Indonesia a disaster-prone region, especially caused by the movement of tectonic plates, one of which is the tsunami. Several tsunami occurs were recorded in Indonesia. Tsunami occur on a large scale and causes losses, both environmental damage and fatalities. Therefore, evacuation planning is needed to minimize the number of fatalities when a tsunami occurs. This study aims to find out the potential threat of tsunami hazard in Ciletuh Bay and analyze evacuation planning in the region. The method used in this research is the spatial modeling method which is divided into tsunami inundation modeling, population distribution, and estimated evacuation travel time. The result of this study is that potential tsunami hazard in Ciwaru Village id found in two hamlets with an area of 104.63 Ha. A total of 590 exposed residents can evacuate within 0 – 15 minutes. The selection of evacuation routes with the fastest travel time is needed so that residents can reach the evacuation collection point before the tsunami arrives. The availability of road access in the hamlet makes it easier for residents in tsunami-exposed areas to reach evacuation gathering points.

The island of Java is located above a plate boundary within the Indonesian archipelago as part of the volcanic arc resulting from the subduction of the Indo–Australian plate beneath the Eurasian plate. Due to its emplacement, it is exposed to several geohazards, including active volcanoes and earthquakes, and its secondary effects (e.g., landslides, tsunamis). Tsunamis have repeatedly hit Java; for example, the 17th of July 2006 caused by an Mw 7.8 earthquake off the coast of western Java, or the 22nd of December 2018 triggered by the collapse of the flank of Anak Krakatau during its eruption. In most cases, tsunamis have a destructive coastal impact and can cause a significant loss of lives. Therefore, it is of high importance to determine areas situated in tsunami risk zones and estimate plans for risk reduction and prevention. We present an ArcGIS-based method to calculate tsunami risk zones for the Special Region of Yogyakarta (Central Java), including the calculation of hazard zones, vulnerability zones, and the estimation of highly exposed areas. The final risk map reflects the current risk zones in the occurrence of a tsunami and should be recalculated and re-evaluated if the environmental and socio-economic conditions change. The results can be used as a base for tsunami evacuation plans and site planning.

This article presents the characteristics of the small islands of Tidore and Hiri, which are vulnerable to the dangers of volcanic eruptions in Indonesia. The physical condition of the area is very important for carrying out a sustainable disaster risk reduction analysis; therefore, climate and topographic data are important to know. The limited availability of data in the study area causes climate data to be obtained from NASA's Earth Science Data Systems (ESDS) and regional topographical presentation of Indonesia's national DEM data. The results show that in the period 2004 to 2014, the temperature in the study area ranged from 292 K to 309 K. The islands of Tidore and Hiri have monthly precipitation between 50 mm to 500 mm.

The Cijulang area is one of the deposits included in the high sulfidation epithermal deposits in Garut Regency, West Java Province. Ore mineralization in high sulfidation epithermal deposits is closely related to the geological structure. The existence of streamflows can be used as a fundamental basis for identifying geological structures. Geological structure identification is done by classifying the orientation angle interval class in stream segments. Each grid unit in the orientation angle interval class stream segment which has the same pattern is controlled by geological factors, including geological structures or the constituent rocks. By utilizing streamflow data, Digital Elevation Model (DEM), and secondary data (e.g., geological features such as structure geology and lithology from previous research data), geological structures can be identified. Faults that can be identified are the Cikahuripan fault, Citando fault, Cisuren fault, and Cibuni fault. These faults affect streamflow by 44.54% in the research area while lithology affects 35.12% of it. The influence of lithology will be greater in lower-order stream segments and the effect of faults will be greater in high order stream segments.

In this study, we focused on the fact that an oblique weir with an opening activates the fluidity of the sediment compared with a conventional continuous fixed one and examined the removal function of the sediment deposited upstream of the weir. Experimental results showed that the weir with the opening increased the fluidity of the sediment deposited upstream of the weir and lowered the riverbed. The scouring section upstream of the weir was divided into a gradually varied flow section and a local flow section based on the bed topography. In the gradual flow section, the descent of water level and riverbed increases linearly as the opening depth increases. In addition, it was shown that the local scour shapes upstream and downstream of the weir were similar to each other as a result of normalization on the representative scale of vertical and transverse shapes. By creating the opening of the oblique weir, the magnitude of the downward flow generated near the left bank was reduced from 45% to 34% of the non-open weir.

The Thornthwaite and Mather water balance method has been widely applied in the world, one of which is in Indonesia. However, almost all studies using the Thornthwaite and Mather water balance method in Indonesia are not validated. Considering that the Thornthwaite and Mather water balance study makes it easier to study hydrology, especially in areas that do not yet have complete and evenly distributed hydrological and meteorological stations. The research locations are in the Wampu sub-watershed, Serayu sub-watershed, Ayung sub-watershed, and Tondano sub-watershed. The method used is the Thornthwaite and Mather water balance with input data on rainfall, temperature, land use, latitude, and soil texture. The validation test was performed using the RMSE equation from the runoff model compared to the observation runoff (river discharge data). The RMSE results of the Thornthwaite and Mather water balance method in the Ayung sub-watershed (42.42%), Serayu sub-watershed (53.77) Wampu sub-watershed (65.58%) and Tondano sub-watershed (83.68%) were classified as weak correlation categories. The comparison results of the Thornthwaite method in tropical areas had greater rain, potential evapotranspiration, and runoff values than other climatic areas. Based on the result, we need to modify the Thornthwaite and Mather method for tropical areas and add a range of 25-30 years of climate data.

In recent years, rainfall-runoff modelling using LSTM has shown high adaptability. However, LSTM requires far more computational costs than traditional RNN. In addition, a different type of RNN, GRU, has been developed to solve this issue of LSTM. Therefore, this study compares the accuracy of the deep learning methods for rainfall-runoff modelling using three deep learning methods in a snow-dominated area. Besides, the setting of hyperparameters may affect accuracy. The accuracy of these deep learning methods was investigated by trying multiple combinations of hyperparameters. The input data were daily temperature data and precipitation data. The results show that GRU gives the highest accuracy in most combinations.

Hydroisotope studies were carried out on Mudal and Clapar springs located in the central part of the West Progo Dome. The research was conducted by taking samples of groundwater in each spring for three periods, representing the rainy (2016), dry (2017), and rainy (2018) seasons. Data on stable isotope content of ¹⁸O and D were analyzed to see the hydroisotope characteristics of groundwater and their relationship to climate change. The results show that the stable isotope content of groundwater in both springs was relatively stable, with insignificant changes over time and season. Mudal springs tend to show light isotopes, indicating deep aquifer or high elevation recharge, less affected by the season. Clapar spring shows heavy isotopes, which may be sourced from a shallow aquifer with mixing/evaporation processes and are more influenced by the season. Meanwhile, the range value of δD in the two springs shows slightly - totally changes, indicating that the D content also changes due to seasons, although it is small. The δD enrichment shows the medium-large change in both spring springs, but uncertainty in Mudal. However, the D-excess value shows that the dry and rainy season conditions, which may be related to temperature or precipitation, are not much different.

The Lower Central Plain of Thailand has a deep and highly irregular basement filled with complex layers of alluvial sandy soil and deltaic clay or silt. The Bangkok Metropolitan region with its high level of infrastructure development is located in this plain. With high population density, the problem of land subsidence is critical. This study uses borehole data and the Kriging method to interpolate the data. A detailed 3D stratigraphic model of the basin is presented and several cross sections along two directions. Seventeen layers and the points used for modelling each layer are presented. The model shows eight aquifers in the Bangkok basin, lying between eight layers of clay, and a bottom layer above the basement. The bottom of the lowest aquifer of the Bangkok aquifer system is 610 m deep. The basement extends down to a depth of more than 2000 m in some places. Our 3D model, which extends to the basement, is of interest for mining and site-specific seismic risk analysis. Moreover, our results can be very useful for groundwater and land subsidence studies.

Sufficient water supply can still be a big challenge in developing countries. A large number of households in Yogyakarta still relay on private dug wells to meet their daily demand. But water from shallow aquifers is prone to pollution from sewage systems, industry and agriculture. To assess the water quality in the basin of Yogyakarta, this study determines the chemical characteristics of the shallow groundwater in anthropogenically influenced and uninfluenced areas in and around the city of Yogyakarta. Therefore, a combination of on-site and laboratory analysis is used to distinguish areas of different water types. The observations give a major ion distribution for the whole research area and show significant anomalies in nitrate and phosphate concentrations especially in the city. Furthermore, high DOC values point out that the aquifer is widely polluted. There is a need for a better groundwater protection and remediation strategy to facilitate future use of those groundwaters.

While basaltic volcanic aquifers are well described in the literature, andesitic groundwater systems are less studied. Nevertheless, these aquifers supply a large population in all the subduction areas, where this volcanism mainly occurs. In Indonesia, the growing needs of the population induce an increase of the pressure on such aquifers. We present in this paper the case study of the Arjuno-Welirang, and compare it with a well-known hydrogeological system, the Bromo-Tengger. Based on geological, geomorphological, and water chemistry data, this study highlights the diversity of andesitic history inherent to this kind of volcanism, and its strong implications on the groundwater availability downstream. The aim of this paper is also to show that simple investigations can help building a preliminary conceptual model (PCM) of complex volcanic settings. Such PCM is needed to define further detailed hydrogeological investigations required to set-up aquifer exploitation, management and preservation rules.

The relocation of nation's capital is one of the government's flagship programs at this time. The lack of information on soil structures that are prone to deformation can bring an impact on the failure of infrastructure development in the areas of New State Capital (known as Ibu Kota Negara/IKN). Therefore, a significant study is important to find out the deformations that may occur in the region as an initial information in determining the location for safer infrastructure development based on the soil structure conditions in the research area. This research used the Differential Interferometry Synthetic Aperture Radar (DInSAR) method with a multi-temporal approach to identify the deformations in the research area. The data included SAR images of Sentinel 1A type SLC with C band (5.405 GHz) for the period 2015-2019. The results confirmed that deformation had been identified in several areas, both those experiencing subsidence and uplifting. The maximum subsidence was 12.97 cm at Sepaku district on period 2018-2019 and the maximum uplift was 10.01 cm on period 2017-2018. The identified areas with deformation generally take place in areas with a high density of buildings, construction areas, road infrastructure, and river alluvial deposits.

A geophysical survey using broadband magnetotelluric (MT) technology was carried out in Suwawa Geothermal Prospect Area, Gorontalo Province, Sulawesi Island, Indonesia. The target of that research is to evaluate the geothermal potential hidden below the surface, based on underground resistivity distribution. However, the information about resistivity alone is not enough to get a proper understanding of the geothermal system in this area. Another important subsurface feature that could be useful for the evaluation is temperature. In this study, an attempt to predict the subsurface temperature using resistivity and limited information from a shallow borehole thermogram was carried out. Employing the dependency between resistivity and temperature an indirect temperature estimator was built, thanks to the applicability of artificial neural network (ANN) to learn the pattern connecting both parameters. Comparing some neural network training data shows that the predictive powers of the calibrated neural network highly influenced by the geological difference between the location of borehole and MT station. The best trained ANN was then used to predict the temperature below the other MT stations. The result shows that a proper ANN architecture is important to improve the deeper temperature estimation. The best ANN estimator was obtained from the BT01 and AMT39 data pair, which has the highest correlation as well. This preliminary study gives useful insight into how resistivity could be an alternative tool to delineate the near-surface temperature profile, in order to get a more comprehensive image of the subsurface geothermal system.

In this study, we investigated the underground structure for Amarapura township, Mandalay region. One of the major structures in Myanmar is the Sagaing Fault system. Several powerful earthquakes have struck along the Sagaing Fault during recent years, one of the largest of which was an M 7.0 event that occurred on July 16, 1956 and caused several casualties. Following the event, we conducted a microtremor survey to estimate the shaking intensity distribution during the earthquake. Seven boreholes were drilled throughout the basin, especially in Amarapura township to evaluate the geotechnical properties of subsurface soil layers. The H/V analysis of the noise measurements reveals frequency peak values ranging from 0.5 to 3 Hz on the Amarapura township. The shear wave velocity becomes less than 190 m/s in some areas, which causes severe damage for buildings in high probability. The sediment thickness values range from less than 50 m to greater than 320 m on Amarapura township, Mandalay region. In this way, the accomplished work has contributed to the characterization of the underground structure and the identification of sites prone to amplify soil shaking during a possible strong earthquake.

Massive groundwater extraction from production wells can trigger seawater intrusion, such as what happened in Sayung District, Demak. Seawater intrusion can be identified using quality analysis in the form of the electrical conductivity of each water sample taken. The research area is located in Sayung District, Demak Regency and is on the north coast, and is composed of alluvium quaternary deposits in the form of clay, sand sediments, and organic material of the plant. The purpose of this study is to determine the distribution of seawater intrusion in Sayung District and to know the prediction of the direction of seawater intrusion to provide an overview of groundwater quality recommendations in the study area to residents. To determine the distribution of seawater intrusion, you can use Electrical Conductivity and TDS (Total Dissolved Solids) data, from the results of the analysis there is a decrease in groundwater quality as indicated by the electrical conductivity value in the range 2,800-3,265 μmnos/cm with slightly brackish salinity and damage levels. categorized as critical and has a relatively high TDS value in the range 1,904-2,220.2 mg/L which is spread in the northern part near the coast including Timbulsloko and Sidorejo villages.

Either P-wave or S-wave tomography has been used to interpret soil stiffness zone to extend subsurface conditions' visibility. The dynamic elasticity moduli have been calculated to connect both seismic wave velocities to geotechnical rationale. However, the interpretation has to be more integrated and less subjective. Fuzzy logic has been applied for both velocities fusion to generate geotechnical cross-sections to diminish the subjectivity. Nevertheless, this is a new application, and it is not known whether this result has a relation to the dynamic elasticity moduli or not. Therefore, this research uses Fuzzy Logic to identify the soil stiffness zone and its relationship to the dynamic elasticity moduli. Meta-hypotheses are produced by possibility function in the early phase of the fusion. The possibility function is a fuzzy set that describes each seismic wave velocities to a geotechnical rationale in a possibility scale. Meta-hypotheses fused into hypotheses: the possibility of solid-state behavior and plastic-state behavior. It is found that solid-state behavior is analog to Bulk modulus, and the plastic state is analog to the elastic modulus. Both hypotheses' extreme values are highlighting the target based on the geotechnical rationale from the possibility function.

The shallow depth water mapping has become important to the study of morphology and resources management of the coastal area. Moreover, for city or urban planning, it can be used for determining the proper location for seaport or tourist destination areas such as diving spots, coral reef monitoring, etc. However, the acquisition of shallow depth water data in a large area is somehow costly. In this paper, we represent an approach of mapping the high accuracy bathymetry with input from open satellite access data and some point measurement of bathymetry in the field (can be from LiDAR, Fathometer, Single Beam, or Multi-Beam). The study area is located in the Florida coastline, the USA that has satellite data from Sentinel-2 while the bathymetry is from a single beam survey. The method is combining satellite-derived bathymetry (SDB) with the regression kriging analysis, which shows a better depth water prediction compared to the SDB alone or the ordinary kriging method. The statistical result of the bathymetry shows the regression kriging has a better mean value, standard deviation and coefficient correlation compared to the true bathymetry value. Thus, this method can be utilized as an alternative method to map shallow depth water.

Water is crucial part in tourism development. However, not all locations have good and accessible groundwater resources. Ngepring Vineyard in Purwobinangun Village, Pakem District, Sleman, Yogyakarta face this problem. Ngepring vineyard is a developing tourism area at southern mountainside of Merapi which is one of geotourism destination in Indonesia. In its development, there were obstacles to fulfill the water supply for tourism and locals' daily use. This research aims to determine groundwater potential zone and recommend a drilling point for a new well. Geoelectric resistivity survey conducted to evaluate subsurface condition by measuring and interpretating rock resistivity properties. Schlumberger Vertical Electrical Soundings (VES) configuration used with a maximum spacing from the center point as far as 250 meters with three VES were measured in study area along two N-S profiles perpendicular to one E-W profile. As the results, there is a sand layer at approximately 80m depth interpreted as aquifer. This result can be used as a preliminary study used to determine potential location for a new water resource in Ngepring vineyard.

Hydrocarbon pollution in the Jlagran area's groundwater, Yogyakarta City, has been going on for more than 20 years. So far, the pollution source has been inferred from a leak in the diesel fuel storage tank from near Train Station. This study aims to prove the claim that the source of hydrocarbon pollutants comes from the location of the fuel storage tank or not. This research was conducted by collecting data on hydrogeological aspects and total organic carbon (TOC) concentration in groundwater, followed by modeling flow and mass transport using Visual Modlfow MT3DMS. The modeling results show that the contamination plume distribution in groundwater at the recent time cannot be caused by only one point source, namely the fuel oil storage tank's location, but also may come from the train maintenance area. It is estimated on this area that the disposal of train maintenance waste of hydrocarbon as a result of poor practices for at least two decades has been developing a residual hydrocarbon zone in the unsaturated zone, and now potentially seeped into the aquifer and also contribute as a source of hydrocarbon pollutant to groundwater.

The northern Semarang area is prone to a land subsidence problem as the underlying soil consists of a thick layer of normally consolidated clay which also exacerbated by groundwater extraction to meet water demand. The downdrag impact on a pile structure due to the water extraction from two major aquifers that have been used for domestic consumption was investigated. A 3D-finite element analysis was performed to a raft foundation with steel pipe piles. The study used Banger polder data and soil characteristics based on previous investigations. The evaluation was done by comparing the results of negative skin friction (NSF) and total settlement within 50 years period under continuous extraction and one without. From the result, the corner pile located farthest from the pump mobilized NSF of 64% of the total negative skin friction which was highest than middle and interior-corner piles of 28% and 20%, respectively. The groundwater extraction was also found to contribute to almost double the settlement in 50 years in the non-piled area, from 0.24 m without extraction to 0.42 m accounted for. Also, the empirical 0.75L_pile for the maximum neutral point of the pile is in agreement in the result of this study.

The effect of urbanization and industrialization in the urban city is soil contamination by heavy metals. This study was conducted to assess Pb, Cu, Zn, and Cd, in the soil of Yogyakarta city and its surrounding, Indonesia. The assessment was done by analyzing 45 surface soil samples in the study area, divided into three-zone. They are divided based on the distance of each zone to the center of the city. The zone III is located in the outermost of the study area, and zone I is inside the city. The results of the study showed that generally, the highest concentration of metals was located in zone I, which is located near or directly situated in a city center. The result indicated that Pb and Cd had the highest pollution index compared to Cu and Zn. The pollition load indeks (PLI) and geoaccumulation indeks (I_geo) calculations in the whole study area showed that the values demonstrated a moderate class in average. Special attention was needed to be given to the zone I, which has a higher PLI and I_geo index to reduce the source of emission for Pb and Cd.

Geosite is a Geological Heritage object in the Geopark area with specific characteristics and is an integral part of the evolutionary history of forming an area. Serpentinite Pucangan is one of the Geosite located in Karangsambung – Karangbolong geopark. This study aims to find out the characteristics of petrography and geochemistry of Serpentinite Pucangan Geosite. The methods used in this study include literature studies, fieldwork research, petrography analysis, ore microscopy analysis, whole rock analysis consist of major element analysis using fusion inductively coupled plasma (Fus ICP) methods, trace element analysis, and rare earth element analysis using inductively coupled plasma mass spectrometry (ICP-MS) methods. Serpentine minerals with antigorite type dominate the petrography composition of Pucangan serpentinite with a little magnetite mineral. SiO₂, MgO, and Fe₂O₃(t) are the major elements with the largest percentage of 37.93%, 5.78%, and 9.73% that have an agreement with the mineralogical composition of the rock that dominated by ferromagnesian minerals. This Geosite is interpreted to be formed due to the metasomatic process when the subduction process is happening in this area in the Pre-tertiary period.

The increasing development in Indonesia today will require higher portland cement consumption. Good quality cement comes from good quality raw materials. A research was conducted in the Gunem area, Rembang, Central Java which is a limestone quarry of PT Semen Indonesia. The research aims to determine physical properties of the limestone and determine the percentage of CaO and MgO and determine the quality of limestone as raw material for Portland cement. This research uses several methods, which are megascopic analysis, petrographic analysis and XRF (X-Ray Fluorescence) analysis. The results shows that wackestone has the lowest content of CaO and the highest content of MgO, while packstone and grainstone have the highest content of CaO and the lowest content of MgO. Packstone and grainstone are classified as high grade for cement raw material, while wackestone is classified as low grade for cement raw material.

Botorubuh Beach is located at Southern Beach of Gunungkidul, in the Southern Mountain of Yogyakarta - Indonesia and is a promontory composed of Middle - Late Miocene igneous rock with a columnar jointing structure. This isolated igneous rock area is surrounded by limestone. Therefore, the regional geological map of Surakarta-Giritontro classifies this area as the Punung-Wonosari Formation which is dominated by limestone. Because of the geological phenomenon of the isolated igneous rock area, it is necessary to study the petrogenesis of the igneous rocks at the area. The petrogenesis research is based on a preliminary study of the petrographical and geochemical characteristics of this igneous rock samples. The petrographic identification of andesite samples shows porphyritic, trachytic, oscillatory zoning, and sieve textures. The results of geochemical analysis (major and trace elements) show that the rock samples are are classified to andesite rocks and calc-alkaline suites. These rocks are enriched in LILEs (Rb, Ba, K) and depleted in HFSEs (Nb, Ti, Ce). Additionally, REE shows a slight enrichment of light-REE and a slight negative anomaly of Eu. The patterns of the trace elements including REE show a typical pattern of calc alkaline arc. Petrographical and geochemical characteristics suggest evidence of magma differentiation process, that is by a mechanism of crystallization fractionation. The andesite was formed in relation to a Middle – Late Miocene paleomagmatism and the Late Miocene-Pliocene subduction zone.

Oyo river deposit is one of the potential resources for small scale sand mining in Yogyakarta. The deposit extends along the upstream to downstream area of the river. A detailed study on textural and mineralogical characterization is aimed for better understanding of Oyo River sedimentation and provenance. Ten sediment samples were analyzed by using granulometry method, these include grain size, morphological and mineralogical analysis. The result shows that the average of grain size changes from coarse sand (0.88 mm) in the upstream to medium sand (0.37 mm) in the downstream. Sorting value is dominated by moderately sorted (0.7lφ - 0.94φ), skewness is dominated by very fine skewed (0.3φ - l.l0φ), and kurtosis is dominated by extremely leptokurtic (2.8φ - 6.5φ). Meanwhile for the grain shape is dominated by oblate and bladed, sphericity changes from elongate to subequant, roundness is dominated by subangular and subequant. Mineralogical composition consists of magnetite, hematite, pyroxene, amphibole, quartz, feldspar, and lithic fragment. Plotting result on triangular QFL (Quartz Feldspar Lithic-fragment) diagram shows that the provenance of Oyo River sand deposit is coming from dissected arc tectonic setting.

The Bagelen district in the southwestern part of Kulon Progo Mountains has a unique aspect in the form of the occurrence of mafic mineral megacrysts in volcanic rocks. This research is conducted to determine the type, the distribution, and the origin of those megacrysts, which are abundant in pyroclastic rocks. Detailed geological mapping on an area of 4 x 4 km with a scale of 1: 25,000 and petrographic analysis were done to explain the geological aspects that led to the presence of mafic mineral megacrysts in the study area. Petrographic analysis shows that the types of mafic mineral megacryst are hornblende, clinopyroxene, and plagioclase. Their features under the microscope observation are oscillatory zoning, half oscillatory zoning, sieve, and breakdown texture. These minerals are found as single crystal fragments and also as clinopyroxene and hornblende cumulate fragments in pyroclastic breccia. Based on mineralogical composition and texture, these mafic mineral megacrysts were formed by fractional crystallization process in the form of crystal settling mechanism. These minerals were initially accumulated in the bottom of magma chamber, then carried upward by rapid magma rising in association with explosive eruption event of Mount Ijo. These minerals were then transported on the surface through the mechanism of pyroclastic flow and were deposited in the valley to form an alluvial fan morphology in the southwestern part of Kulon Progo Dome.

Groundwater is a very important water resource at Kumamoto City. Kumamoto City is the capital city of Kumamoto Prefecture, which is located in the Kyushu region, Japan. All domestic water is obtained from groundwater in Kumamoto City. Modeling groundwater is a difficult issue. Conditions under the ground are complex, and difficult to be obtained. Even the delineation of a groundwater basin is frequently unknown. Nowadays, deep learning is a hot topic in many research fields including geoscience. A recurrent neural network (RNN) is a type of deep learning that is suitable for time series modeling. Then, it has been successfully applied for groundwater modeling. Therefore, this study utilized a new type of RNN, Long and Short-Term Memory (LSTM) network, to model groundwater level at a monitoring well within Kumamoto City. The results in this study showed good agreement with the observed groundwater. In addition, it is known that severe earthquakes in April 2016 affected the groundwater level around Kumamoto City. The groundwater level model by LSTM was also utilized to estimate the effects of the severe earthquakes on the groundwater level. The results indicated that the earthquakes may have increased the groundwater level at Kumamoto City by more than 3 m.

Future climate projections are valuable datasets to investigate the impacts of future climate changes on natural disasters such as intense precipitation, severe flood, and drought. However, they are too coarse depending on the purpose, and downscaling is required in such a case. There is nowadays a downscaling technique using deep learning such as CNN. Atmospheric information can be used as an input for precipitation downscaling by means of Convolutional Neural Network (CNN). For such precipitation downscaling, the spatial and temporal resolution of the atmospheric information may be important. This study obtained atmospheric information from a coarser reanalysis dataset and a finer reanalysis dataset as input for precipitation downscaling. As a coarser reanalysis dataset, ERA-Interim was selected. As a finer reanalysis dataset, ERA5 was utilized. Then, this study investigated the effect of spatial and temporal resolution of input data on the estimation accuracy of precipitation downscaling by CNN. For simplification, daily average precipitation at a watershed was used as the target data. The results show advantage of the use of a higher resolution as input can improve the model accuracy.

The southern coastal area of Lebak, Banten is the southern region of Java which is prone to tsunami disasters. There is evidence of past tsunami events in the southern region of Java. However, not all tsunami deposits have identifiable sedimentological and micropaleontological traces. Geochemical proxies and artificial intelligence with machine learning methods can be used to identify paleotsunami deposits. Machine learning methods that can be used to cluster paleotsunami deposits are Agglomerative Hierarchical Clustering (AHC) and Support Vector Machine (SVM) with validation of model accuracy using the Receiver Operating Characteristic (ROC) and Area Under Curve (AUC) methods. Input data are XRF analysis data and macroscopic core sample description data. The output from data processing is in the form of prediction of tsunami and non-tsunami deposits at each depth of core data sample. The data is correlated and interpreted to identify tsunami events that occurred in the past. The identification results show that the tsunami deposition in the research area, namely the area around the Bagedur coastal coast and Bolang village had tsunami deposit characteristics based on macroscopic description, XRF analysis, and artificial intelligence clusterization. It is also thought to be correlative with the tsunami deposition of previous research in the area around the Binuangeun coastal coast.

This research aims to determine the depositional facies from electrical log data using the gradient boosting classifier method, which comprises a powerful algorithm. The electrical logs used are gamma-ray (GR), resistivity (ILD), neutron porosity (NPHI), and density (RHOB), while the output is in the form of images. The training data consists of 4 wells in Jambi sub-Basin, South Sumatera Basin, while the testing data comprises 5 wells with gamma-ray, resistivity, NPHI, and RHOB as input. Several scenarios are used to predict the facies model, namely training and validation dataset by using and isolating facies in well combination input, and with or without feature augmentation. Furthermore, the values collected were validated using F1 score. The result showed that 85.5% and 84.7% of F1 scores were allocated to training and validation to increase accuracy in scenarios without facies isolation and with feature augmentation. Therefore, the gradient boosting classifier method is reliable enough to characterize depositional facies in the associated area of interest.

Mount Lawu is a stratovolcano in Central Java that holds a large geothermal energy potential. Within Mount Lawu Geothermal Area, several thermal manifestations could be located one of them being Candradimuka Crater located at the proximity of Mount Lawu peak. This study aims to assess the gas geochemistry in Candradimuka Crater by obtaining gas sample within the crater area. Gas geochemistry analysis uses geothermometer, geoindicator, and N₂-He-Ar ternary diagram to analyse the subsurface condition. The analysis reveals that the fluid circulating in the crater originated from meteoric water and that Mount Lawu reservoir temperature ranged between 250°C - 289°C. Based on geological observation and gas geochemistry, Candradimuka Crater is located within the upflow zone of Mount Lawu.

Debris avalanche deposit is formed by the failure of volcanic edifice and has a high potential to directly impact human civilization. The famous characteristic landform of debris avalanche deposit is hummocky hills. To understand the dynamics of avalanche flow, we investigate the morphometric characters of debris avalanche hummocks from Gunung Gadung in Raung Volcanic Complex. The collapse of Gunung Gadung follows two main flow direction with two different kinds of debris avalanche, i.e., freely spreading and valley filling. Our study recorded that there is no significant correlation between hummock size and distance from the source. The distribution of Gadung hummock size is mainly controlled by pre-existing morphologic feature such as Iyang-Argapura Volcanic Complex and Meru Betiri Mountains. We identify four domains area of Gadung debris avalanche flow based on hummock size distribution, which are Toreva domain, Hummock domain, Collision domain, and Oblique collision domain. Hummock orientation and displacement angle of Gadung debris avalanche deposit depend on structural regime existed in certain area. Compressional regime may occur because of collision between Gadung avalanche flow and Iyang-Argapura Volcanic Complex, or shifting of main flow direction. Meanwhile, extensional regime may happen due to decreasing in slope and spreading of avalanche flow.

We present the result of morphostratigraphic analysis and geological field observation to identify the distribution of scoria flow deposit related to the caldera-forming eruption of Lautan Pasir caldera as the youngest caldera in Bromo-Tengger caldera complex. Morphostratigraphic analysis derived from digital elevation model and volcanic stratigraphy shows that products of Lautan Pasir caldera-forming eruption(s) mainly distributed to the north filled up the Sapikerep valley, and further to the north formed Sukapura distal fan. While to the south, it filled the valley between Ijo and Old Semeru. Field observation in the deeply dissected part of Sapikerep valley found two massive pyroclastic flow deposits separated by lava flow. Above the lava flow is scoria rich pyroclastic flow deposit typical of Lautan Pasir caldera-forming eruptions. Below the lava flow is scoria poor pyroclastic deposit of older products, most likely, of Ngadisari caldera. The distribution of Ngadisari caldera-forming eruption products is very limited considering the following massive volcanism of Lautan Pasir caldera. This outcrop might provide the key information to further reconstruct the volcanism stage of Bromo-Tengger caldera complex

Fly ash and Bottom ash (FA-BA) are solid waste produced from the coal-generated power plant. FA consists of fine powder particles with diameters varying from 0.5-100 µm, while BA consists of coarser particles with a diameter of 0.125-2 mm. FABA and feed coal samples were collected from the power plant in Lampung to distinguish the effect of power plant operating conditions on FABA composition. Feed coal characteristics were examined by proximate and petrography analysis. Organic and inorganic components of FABA were identified using petrography analysis, while the detailed mineralogical composition of FABA was determined using X-Ray diffraction analysis. Moreover, major oxides of the feed coal and FABA were determined using inductive ICP-AES. From the analysis, it was found that FA composition is mainly organic material in the form of unburned carbon (UC). The abundance of UC content (up to 74.68%) indicates the inefficiency of the coal combustion process. In terms of inorganic, quartz is the most abundant mineral found in the FABA sample, up to 50.15%, in contrast to the glass content that was only 17.41%. A minor amount of spinel (0.03-2.00%) was found associated with Fe-oxide mineral. Kaolinite was only found in the BA sample from a landfill source and interpreted as external input from the dumping ground. The high content of UC and quartz will decrease the compressive strength of the material construction product providing a negative impact on the utilization of FABA.

Lithium is an alkaline, metallic element found primarily in the earth's crust and seawater. Recently, the industry's need, especially lithium batteries, has been increasing. Lithium exploration is directed to various geological environments that have the potential to contain lithium. Based on previous research, mud products from mud volcanoes can contain lithium. We conducted this research to determine the potential for lithium enrichment found in mud produced by mud volcanoes in Lapindo, Mount Anyar, and Buncitan. Samples were prepared to analyze petrography, X-ray diffraction (XRD), ICP-MS, and ICP-AES. Mineralogically, the mud sample comprises smectite, kaolinite, quartz, plagioclase, clinopyroxene, calcite, pyrite, and dolomite. Lithium in the mud sample has an average concentration of 92.5 ppm with the highest concentration of 130 ppm from the Lapindo Mud volcano. The lowest concentration of 70 ppm comes from the Buncitan Mud Volcano sample. Based on its mineralogy and structure, the dominant of smectite and kaolinite clay minerals can bind the lithium. Lithium in the study area is thought to come from altered rocks below the surface, which migrate and are bound to clay minerals predominantly found in subsurface mud.

The exploration of nuclear minerals in Mamuju, West Sulawesi has been started in 2013 by the Center for Nuclear Minerals Technology (CMNT) – Badan Tenaga Nuklir Nasional (BATAN). There is a strong indication of uranium (U) and thorium (Th) minerals occurrences in the location. To follow the exploration result up, a resources assessment is needed. Due to the limited early exploration data, the concept of undiscovered resources can be used. Of all resource assessment methods suggested by International Atomic Energy Agency (IAEA), Energy Research and Development Administration (ERDA) method is the most appropriate method to be applied in the Mamuju case. In this research, Pocos de Caldas, Brazil (Osamu Utsumi Mine for U reference and Morro do Ferro Area for Th reference) was selected as control area due to its similarity on the geological condition and its more-advanced exploration stage compared to Mamuju. All the parameters for the assessment can be determined with the ERDA method based on the available information of the control area.

The benefits of clay minerals are currently numerous. Therefore, this study aims to determine clay minerals' characteristics in the mud material recommended for use, especially in the ceramic and cosmetic industry. This research is located in Bledug Kuwu, in Kuwu Village, Kradenan District, Grobogan Regency, Central Java Province. Bledug Kuwu produces mudflows composed of gravel, sand, silt, plastic clay, and water. Field observations and sampling were carried out on any differences in the morphology of the existing mud volcanoes, namely inactive craters and active griffins, with an average area of about 0.8–5 meters of mud material distribution. Samples were prepared to analyze X-ray diffraction (XRD), cation exchange capacity (CEC), pH, grain size distribution, plasticity test, swelling test, shrinkage limit test, and specific gravity. The results of the analysis show that the dominant clay minerals were smectite, followed by kaolinite and illite minerals, with dominant clay to silt grain sizes, plasticity levels of 24.78% to 55.48%, swelling percentage of 7.8%. up to 12.5%, with shrinkage limits of 9.36% to 14.83%, specific gravity values of 2.50–2.84, cation exchange capacity (CEC) values of 9.96–20.47 meq/100g, and the pH value shows the numbers 8.01– 8.40. These characteristics can be recommended to use clay minerals as raw material for cosmetics and ceramics.

Toka Tindung Project is a low sulphidation epithermal gold deposit, which is located in North Sulawesi, Indonesia. To be able to maximize the production yield of the Toka Tin-dung Project, it is important to understand the characteristics of the ore along with its mineral associations. This paper discusses the ore characterization and its mineral associations in "X" pit using thin section analysis to define the rock characteristics and hydrothermal alteration, X-Ray Diffraction (XRD) to identify the hydrothermal alteration minerals, and ore microscopy to identify the type of ore minerals. The study area is occupied by three alteration zones, namely silicification, advanced argillic and intermediate argillic alteration. The silicification is characterized by quartz with accessory minerals such as kaolinite, smectite, and celadonite. The advanced argillic alteration is typified by kaolinite, with minor quartz. The intermediate argillic alteration is characterized by clay minerals such as illite, mixed illite/smectite, smectite, and minor quartz minerals. Mineralization in "X" pit is in the form of sheeted vein type quartz with colloform texture, and the ore minerals are found as sulfides such as pyrite and sphalerite.

Kabaena Island is one of the areas in Southeast Sulawesi that has the potential for chromite deposits. This paper is aimed to provide information on the mineralogical aspects of chromitite from the research area. Back-scattered electron (BSE) imaging and chemical analysis of chromite were performed using an electron microprobe. Chromite deposits in the study area are of podiform-type. Chromite is massive and brecciated. Based on the content of Cr # = Cr/(Cr + Fe³⁺) of the chromite, comprised between 0.61 and 0.74, the studied chromitite can be classified as Cr-rich. The only PGM (Platinum Group Minerals) found in several chromitite samples is laurite (RuS₂). PGM occurs enclosed in chromite crystals and in the contact with microfractures of chromite crystals.

We present the first finding of skarn rocks in Cemorosewu area of East Jiwo Hill, Bayat, Central Java, Indonesia. The geological conditions of this area which related to the appearance of the skarn is also reported. The methods used in this research are DEM acquisition using drone to generate basemap for geological mapping and thin section petrographic analyses. The geological map shows that Cemorosewu area consists of metamorphic rocks (mica phyllite, graphite phyllite, with quartzite and marble lenses), sedimentary rocks (carbonate breccia and siltstone), and igneous rock (microdiorite). Based on the field observation and geological map, the regional metamorphic rocks are the oldest units in this area followed by sedimentary rocks and igneous rock which intruded both rocks. Skarn rocks were cropped out as a boulder along the Kluwihan creek with the maximum size of 8 m in length. The skarn consists of garnet, clinopyroxene, zoisite, actinolite, and minor quartz. Metasiltstone and skarn rock are suggested formed by contact metamorphism of microdiorite intrusion. The marble, which lenses within the phyllites, is suggested to be the protolith of the skarn formation in this area.

The offshore North Sumatra Basin is one of the hydrocarbon-prone basins in Indonesia. The Malacca Formation acts as the reservoir in this basin. However, there are some drilling problems caused by abnormal pore pressures. Overpressure analysis is carried out so that drilling activities are avoided from drilling problems such as kicks, blowouts, stuck pipes, loss circulation, and collapse. This study aims to analyze the overpressure in the "APR" block, offshore North Sumatra Basin, which includes determine the depth of the top overpressure and the mechanism of overpressure formation. In the research area, analysis of 3 exploration wells was carried out. Overpressure is analyzed based on well log data, and pressure test data using the Eaton method (1975) supported by other data such as LOT (Leak-Off Test) data, drilling reports, mudlogs. At Well A, top overpressure depth is ± 3235 ft TVDSS (true vertical depth sub sea). At Well P, top overpressure depth is ± 3065 ft TVDSS, and at Well R, top overpressure depth is ± 2901 ft TVDML (true vertical depth mud line). The overpressure generating mechanism in the study area is caused by the loading mechanism (disequilibrium compaction) and caused by the nonloading mechanism (hydrocarbon buoyancy).

The South Walker Creek coals are moderately to highly developed fracture systems. These fractures can be recognized from the top to the bottom of the seam, with both open and closed apertures. They are filled with several different minerals, occurs either as single-phase infillings (monomineralic), or as mixed mineral deposits (polymineralic). This paper presents scanning electron microscope (SEM) analysis of mineralogical association within coals fractures or cleats, as well as their origin and phase of development. SEM-EDS analysis indicates that the polymineralic cleats seem to be more common in the coal seam compared to monomineralic cleats. The polymineralic cleat infillings are composed of clay minerals, carbonates, and other minerals, such rutile and apatite, with minor occurrences of diaspore. This polymineralic association within the single cleat spaces represents a multi-phase minerals formation, as a result of different stages of epigenetic activity. The hydrothermal fluid circulation are responsible for this epigenetic process, they are re-opened previous minerals filled cleats and transformed pre-existing mineral within the cleats, and/or to remobilization earlier minerals, which then precipitated in the cleat as epigenetic minerals.

Reservoir monitoring is one of the most important aspects in oil and gas field management, because it provides industries with the required data in hydrocarbon optimization. This is often carried out in Indonesia by the TAC Pertamina-Pusako Betung Muaro Senami Jambi (PBMSJ), an organization responsible for the management and coordination of oil well activities. In 2012, the organization conducted passive seismic data acquisition and series of drilling campaigns, which successfully increased oil production in Betung Block from 43 to 652 bopd. This campaign was successfully carried out through one and two wells in 2013 and 2014, respectively. Furthermore, the pre-2017 interpretation describes the Betung Anticline as a relatively symmetrical and low angle N-S trending field, which defies the South Sumatra Basin Northwest-Southeast regional trend. This anticline, bound by two high angle normal faults, is unable to define the LKO/OWC position, leading to the consideration of a more integral interpretation approach by the PBMSJ team in early 2017. The procedure was conducted through the use of a 2d seismic line bounded with new wells and SRTM imagery, to combine subsurface structural data with the surface fundamental analogue. In 2017, a passive seismic study was repeatedly conducted in the Betung field, with only 30 measuring points. The urgency in identifying the reservoir is essential within the petroleum industry, in order to produce sufficient hydrocarbons. It is also essential in confirming the potential uses of microseismic data in storage decision-making, through a dataset acquired in Betung, based on reservoir management.

Hydrocarbon-bearing reservoir shows attenuation on seismic section, but the use of attenuation in hydrocarbon exploration is less popular than other attributes. This is due to the sophisticated and advanced technology required to measure attenuation. Meanwhile, some studies were designed to estimate attenuation by formulating rock quality factor equations from a wire-line log, although others run on sandstone samples. Therefore, this study aims to estimate rock quality factors in carbonate rock of Kujung Formation using three different methods, discriminate hydrocarbon-bearing reservoir, and identifying the impact of carbonate facies. The results showed the P-wave quality factor method is sensitive to discriminate high gas saturation on facies A. Meanwhile, the QsQp ratio is sensitive to discriminate shale and carbonate. The SQp and SQs methods are sensitive to discriminate hydrocarbon-bearing reservoirs and less affected by carbonate facies. The novelty of this is to estimate the rock quality factor from various methods and identify the impact of facies in hydrocarbon identification, especially for carbonate reservoirs in Northeast Java Basin. Therefore, a new understanding of facies impact on rock quality factor contributes to choosing the best methods in discriminating pore-filling fluid identification.

The presence of pyrite in sandstone reservoirs will cause a problem known as low resistivity reservoirs case. The impact of pyrite volume in sandstone reservoirs is very important to be determined, especially to conduct its resistivity correction factor (Rcf). This research was done in the laboratory used nine sandstone pseudo-cores with various pyrite contents. Some data parameters such as voltage (V) and current (I) are directly measured and others (resistance R and reservoirs resistivity Rt) are calculated. The resistivity of pseudo-core data is calculated using the combined method between Ohm Law and Wenner. The result of this research shows that pyrite will reduce sandstone reservoirs resistivity exponentially. Pyrite will significantly reduce reservoirs resistivity if its presence > 4% and the Rt needs to be corrected. Plotting data between Rt and pyrite volume number for every Sw line can guide us to build a resistivity correction factor (Rcf). This Rcf will drive us to obtain the original resistivity reservoirs (Rto) from apparent well log resistivity reading (Ra) in case of low resistivity caused by pyrite mineral.

The Batu Ayau Formation in the Kutai Basin has coking coal deposits that have the potential to be processed into coke. Analysis using organic petrography method is an important parameter to identify the composition of the coke product to determine the coke quality. The purpose of this study was to determine the composition of the coke products made from coking coal of Batu Ayau Formation in Kutai Basin, Central Kalimantan. Petrographic analysis on 12 samples obtained in Kal-Teng seam showed that the percentage of coke products varied. Carbon in the binder phase is 85.60 - 92 vol.%, then the form of carbon in the filler phase is 7.45- 13.64 vol.% and a small part of other than carbon material (miscellaneous categories) of 0-0.73% vol. The dominance of inert organic as a filler of the coke wall was identified. The studied coke which is originally made from coking coal with moderate volatile values shows that the coke is ideal in term of its petrographic composition.

Plover Sandstone have been widely known as a good quality of oil and gas reservoir in NW Australia. As the continuity of NW Australia margin, outer Banda Arc become the distribution area of the equivalent of Plover Sandstone units. Therefore, a clear distinction and characterization of equivalent of Plover Sandstones distributed in this area is needed. Thick unit of quartz rich sandstone is scrap out in south Savu Island. Refers to the location where the lithology is found widely distributed, the unit is suggested to be called as Pedaro Formation. The characteristic of the lithology is determined through detailed measured section from two trajectories and laboratory analysis, including fourteen samples of petrography analysis, eight samples of Scanning Electron Microscope (SEM) analysis, and three samples of X-Ray Difraction (XRD) analysis. The lower part of the unit is initiated by braided fluvial conglomerates which gradually become tidal sand flat association of shale layers, coal seams and sandstone insertion. While the upper part of the unit is consisting of thick bedded quartz sandstone with thin siltstone insertion, deposited in the shoreface environment. Those facies association developed at transgressive conditions in the estuarine environment. The characteristic of the sandstone unit of Pedaro Formation is thickly bedded quartz wacke to quartz arenite, white to light grey in color, moderately to very well sorted, mostly mature sand. Pedaro Formation is identified to be deposited at Early Jurassic in interior craton tectonic setting. The characterization of sandstone unit of Pedaro Formation is showing that the unit can be correlate to the equivalent of Plover Sandstone found in Timor. Sandstone unit of Pedaro Formation can play a role as reservoir candidate in petroleum system of Savu and surrounding area.