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INDONESIA
IJOG : Indonesian Journal on Geoscience
Published by Geological Agency of Indonesia
ISSN : 23559314     EISSN : 23559306     DOI : -
Core Subject : Science,
Earth & Planetary Sciences
The spirit to improve the journal to be more credible is increasing, and in 2012 it invited earth scientists in East and Southeast Asia as well as some western countries to join the journal for the editor positions in the Indonesia Journal of Geology. This is also to realize our present goal to internationalize the journal, The Indonesian Journal on Geoscience, which is open for papers of geology, geophysics, geochemistry, geodetics, geography, and soil science. This new born journal is expected to be published three times a year. As an international publication, of course it must all be written in an international language, in this case English. This adds difficulties to the effort to obtain good papers in English to publish although the credit points that an author will get are much higher.
Arjuna Subject : -
Articles 796 Documents
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Hyperparameter Tuning on Machine Learning-Based Landslide Susceptibility Mapping (Case study: Palu City and Its Surrounding areas) Sukristiyanti, Sukristiyanti; Pamela, Pamela; Putra, Moch Hilmi Zaenal; Arifianti, Yukni; Rozie, Andri Fachrur; Lestiana, Hilda; Susantoro, Tri Muji; Sumaryono, Sumaryono; Kristiawan, Yohandi; Putra, Iqbal Eras
Indonesian Journal on Geoscience Vol. 12 No. 1 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.1.43-53

Abstract

Landslide susceptibility mapping (LSM) produces a zonation map of landslide susceptibility levels, representing the future probability of landslides. It is necessary to give a guideline regarding spatial planning. A machine learning method was used, namely a random forest (RF) algorithm to map landslide susceptibility in Python. The case study is Palu City and its surrounding areas, which were attacked by a big earthquake on September 28th, 2018. Some earlier LSM studies did not discuss hyperparameter tuning, and several others did not mention the training accuracy. Therefore, this study is to find out whether the fast model without hyperparameter tuning and frequently overfitting, can well produce landslide susceptibility maps. The research questions were addressed by comparing two landslide susceptibility maps built with and without hyperparameter tuning using receiver operating characteristics (ROC) and landslide density (LD) analyses. This study shows that the area under the curve (AUC) of the landslide susceptibility map from the fast RF model without hyperparameter tuning is as high as the AUC from the tuned model map. It also happened in both landslide density (LD) maps, and there is no anomaly in the fast model map. Nevertheless, there are strange appearances in the fast model map. Therefore, hyperparameter tuning to obtain the optimal model with no overfitting is mandatory to predict landslide susceptibility spatially.
Land Management for Reducing Bank Erosion: Using AHP Method and GIS Technique: A Case Study in Dibru River Basin, Assam India Sonowal, Gulap; Thakuriah, Gitika
Indonesian Journal on Geoscience Vol. 12 No. 1 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.1.25-41

Abstract

The site suitability for land management in reducing bank erosion is an important step towards sustainable development by adopting conservative measures. Land is considered to be very crucial for maintaining an ecosystem which is helpful to sustaining all forms of life. The increasing bank erosion day to day has been one of the common issues in Assam. The present study aim is to identify the sensitive areas of the bank erosion within the Dibru River Basin. Multicriterion calculation was carried out using geographic information system (GIS) technique to help the choice makers in identifying the fit sites of bank erosion. Different parameters which were considered for multicriterion evaluation, ie. landuse-landcover, geomorphology, soil capability, soil texture, slope, and river distances were taken for identifying the vulnerable zones of bank erosion. Analytical hierarchy process (AHP) was used to find the sensitive areas of the bank erosion for land management by weighted sum of different parameters. The suitability site map was classified into low, moderate, and high erosion zone. This map would help implement some preventive measures to mitigate the bank erosion within the Dibru River Basin.
Ambient Noise Tomography Around The Banda Arc Study Case: Before Earthquake of February 2nd, 2022 Raharjo, Wiji; Palupi, Indriati Retno; Madona, Madona
Indonesian Journal on Geoscience Vol. 12 No. 1 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.1.55-63

Abstract

Banda Arc is one of the vulnerable areas in Indonesia. It is trapped by the slab coming from AustralianEurasian Plate with the S ̶ N direction and the slab coming from Pacific Plate with the E ̶ W direction. Because of its location, it has a high seismicity, for example there was an earthquake that raised a big tsunami in 1852. On February 2nd, 2022, the newest earthquake with magnitude of 6.2 hit the Banda Arc. In many cases, earthquakes are damaging disasters, because their surface waves are shocking through anything they pass. Nowadays the surface wave is used to get the subsurface description and the variation of its velocity, and ambient noise tomography (ANT) is one way to solve it. By using some analyses like cross correlation and fast fourier transform (FFT) from the earthquake waveform three days before February 2nd, 2022, the depth and velocity group around the Banda Arc can be known. There is an indication that it was influenced by the ocean wave, which became wider and close to the main shock. Besides that, ANT result shows that the low velocity anomaly was distributed around the deepest area of the Banda Arc, because the energy absorbed more there, besides in the near location of hypocenter and resulting low velocity anomaly. It is shown that the low velocity anomaly can show how the geological condition is.
Utilization of 222Radon and Stable Isotope for Investigating Potential Tailing Storage Leaks: A Case Study from Azurite Gold Mine, Central Kalimantan Siti Rofikoh; Iskandar, Irwan
Indonesian Journal on Geoscience Vol. 12 No. 1 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.1.65-74

Abstract

Azurite Gold Mine is an open pit project in Central Kalimantan which has produced mine tailings from the mining activities. There are various types of tailing storage facility (TSF) methods, e.g. dam tailing, landfill, and backfill to ex-mine void. Azurite Gold Mine stores their tailings in an inactive mine pit, named In-pit Seroja. The tailing placement into the inactive mine pit has less environmental impact compared to dam tailing as long as potential leakage of water-tailing into groundwater can be managed properly. The research objective is to investigate the potential tailing storage leaks into groundwater, and to determine contribution of waste dump at the northern part of In-pit tailing placement. 222Rn measurements and stable isotope analyses were performed for this work. Dissolved 222Rn from water samples has the concentration value between 1070 and 4940 Bq.m-3 indicating the existence of permeable zone around the In-Pit Seroja inactive mine pit. The high 222Rn concentration value is coexisting with the presence of faults, especially some intersection faults. Hydrogeochemical data shows that most groundwater is included to bicarbonate type except one groundwater sample near the waste dump is the sulphate type. Based on an isotopic analysis, the ratio of δ2H ranges from -132.55 to -6.268 ‰ for rainwater samples, -66.621 to -58.09 ‰ for groundwater samples, -97.092 to -48.43 ‰ for surface water samples, and -66.834 to -45.889 ‰ for water-tailing samples. The isotopic ratio δ18O ranges from -17.795 to -2.526 ‰ for rainwater samples, -10.164 to -8.93 ‰ for groundwater samples, -13.912 to -7.714 ‰ for surface water samples, and -9.352 to -2.864 ‰ for water-tailing samples. Water-tailing has different typical stable isotope composition compared to groundwater and surface water. Heavier δ18O and δ2H ratio indicates that water-tailing has already heated by intense evaporation process. Based on hydrogeochemical and stable isotope result, combined with groundwater flow analyses, it can be concluded that there is no leakage from water-tailing into groundwater and surface water around the area.
Shotwavemod: An Open Package For Acoustic 2D/3D Seismic Wavefield and Shot Acquisition Modeling Using the Pseudo Spectral Element and Finite Difference Methods Abdullah, Agus; Pranowo, Waskito; Ahmad Zaky, Dicky
Indonesian Journal on Geoscience Vol. 12 No. 1 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.1.75-87

Abstract

Shotwavemod is an open package for 2D/3D acoustic seismic wave simulation, using the Pseudo Spectral Element and Finite Difference Method. It can also be used for forward modeling of seismic reflection acquisition. The shotwavemod offers straightforward execution of the simulation process, yet customizable parameters. The algorithm was optimized using vectorization and parallel computation to speed up the computational time. The simulation results of the Pseudo Spectral Element Method was compared to the Finite Difference Method. It is observed that the Finite Difference Method resulted in ringing artifacts as a numerical dispersion, particularly for higher frequencies. Nevertheless, with higher computational cost, the Pseudo Spectral Element Method effectively handles this numerical dispersion issue. The shotwavemod was tested for a complex velocity model of the Marmousi. The results are quite promising, where shot gathers of seismic reflections are successfully established corresponding to the complex structure of the Marmousi. The shotwavemod is accessible to the public, and is a suitable tool for educational and research purposes involving seismic wave simulation.
Zonality of Gold Ore and Prospects of Gold-Quartz-Sulfur in Khauau Deposit, Binhvan Commune, Chomoi District, Backan Province, Vietnam Dat, Nguyen Van; Tuan, Le Canh; Son, Trinh Hai; Linh, Nguyen Thi Hoang
Indonesian Journal on Geoscience Vol. 12 No. 2 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.2.199-215

Abstract

Khauau gold deposit, Binhvan commune, Chomoi District, Backan Province, Vietnam, is located in the Dong Bac Bo intracontinental orogenic belt. This is one of the important gold mineralization areas of Vietnam. To study the zonation of mineralization and to predict the prospect of deeply hidden buried gold ore, a research was conducted based on mineral facies analysis, fluid inclusion thermometry, ICP-MS chemistry, and morphological orebody size. The results indicate that the gold mineralization is derived from medium to medium–low temperature hydrothermal fluids associated with deep-seated formations. Inclusion homogenization temperature is from 170 to 310o C, and the main ore mineral components include pyrite, arsenopyrite to a lesser extent galena, sphalerite, and chalcopyrite. Gold mineralization-quartz-sulfur Khauau deposit is divided into three zones, which from the top to the bottom is as follows: ore zone 1 is gold-quartz-pyrite poor sulfur; ore zone 2 is gold-quartz-polymetallic; ore zone 3:is gold-quartz-arsenopyrite and pyrrhotite. Ore bodies are likely located at the depths of 125 to 540 m with many extending beyond 400 m. The depth of ore-forming processes is 562 m and the zoning coefficient of Kz= 0.83. Accordingly, it is possible to predict the prospect of the Khauau gold deposit, Binhvan commune, Chomoi District, Backan Province, to a depth of more than 500 m, and possibly extend to depths of up to 5 km.    
A Critical Distribution of Groundwater Infiltration Status on Agricultural Land Use in Manyaran, Indonesia Mujiyo, Mujiyo; Febryana, Nesia; Suyana, Jaka; Komariah, Komariah
Indonesian Journal on Geoscience Vol. 12 No. 2 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.2.249-265

Abstract

Agricultural land is vulnerable to drought disasters, and effective groundwater management is needed by identifying soil characteristics that support water infiltration. This study aims to assess the criticality of groundwater infiltration distribution in agricultural land in Manyaran District, and the relationship between soil physical characteristics and soil infiltration criticality, so that management strategies can be formulated to increase groundwater infiltration. The assessment uses an assessment method based on The Regulation of The Minister of Forestry P. 32/ Menhut-II/2009, which combines parameters such as soil type, permeability, slope, rainfall, and land use. It is modified by observations of important soil physical properties that affect hydrological processes, including soil texture, bulk density, and porosity, integrated into the analysis. Sampling points were determined using purposive random sampling in the land map unit obtained from thematic map overlay. The influence of land use factors on groundwater infiltration criticality using ANOVA data processing, while the physical properties that most determine infiltration conditions were identified through the Pearson correlation test. The results classify groundwater infiltration status into six categories: good, normal, light critical, moderate critical, critical, and heavy critical. Heavy essential catchment areas, especially in rice fields, are characterized by low soil permeability, porosity, and bulk density. These findings underscore the need for improved soil management practices for groundwater infiltration, such as the addition of organic matter and the implementation of ecological drainage systems, to increase water infiltration and reduce the risk of drought in the area.
Uneven Land Subsidence Patterns Along Java's Northern Urban Corridor (Pantura Route) from 2.5D SBAS InSAR Approach Janur, Afif; Harintaka, Harintaka; Suhadha, Argo Galih
Indonesian Journal on Geoscience Vol. 12 No. 2 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.2.281-300

Abstract

Land subsidence is a phenomenon that occurs in many parts of the world, particularly in coastal plains and river delta areas, including the north coast of Java, commonly known as ‘pantura’. By utilizing satellite time series data, land subsidence along the north coast of Java was detected using The Small Baseline Subset (SBAS) method. Additionally, combining data from different Sentinel-1 orbit directions (ascending-descending) enables the production of a more accurate 2.5D model. This research aims to calculate the rate of land subsidence on the north coast of Java from 2020 to 2023 using the 2.5D model, and to compare the results with CORS processing results. Recent identification of land subsidence highlights that residential areas and rice fields are highly vulnerable to potential subsidence. The 2.5D model in the up-down (UD) direction shows the highest land subsidence occurred in Demak Regency at 146.45 mm/year, Semarang City at 144.34 mm/year, and Pekalongan Regency at 137.94 mm/year. An accuracy assessment was performed using twelve CORS stations, showing RMSE values ranging from millimeters to centimeters: vertical ascending at 16.5 mm, vertical descending at 18.6 mm, UD at 8.8 mm, and East ̶ West (EW) at 26.3 mm.
Petrographical and Geochemical Characteristics of Felsic Volcanic Rocks in the Upper Part of The Khorat Plateau, Thailand Singtuen, Vimoltip; Seela, Thatchapon
Indonesian Journal on Geoscience Vol. 12 No. 2 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.2.231-248

Abstract

The felsic volcanic rocks distributed in the western part of Nong Khai and Udon Thani Provinces are part of The Loei-Phetchabun Volcanic Belt. This study aims to investigate the petrography and geochemical characteristics of felsic volcanic rocks to classify specific names of rocks and explain their occurrences. The textures and compositions by petrographic analysis classify the studied rocks into four types: (1) rhyolite porphyry, (2) crystal tuff, (3) eutaxitic rhyolite porphyry, and (4) hornblende-biotite diorite. In addition, the total alkaline versus silica (Na2O+K2O/SiO2) ratios classify these rocks into rhyolite, dacite, and basaltic andesite/diorite intrusion. Moreover, the major oxides and trace elements indicate that these volcanic rocks were generated from tholeiitic, transitional, and calc-alkalic magma series that formed along volcanic arcs. Therefore, the subduction of at least two tectonic terranes in the area may lead to the formation of the volcanic arc (felsic volcanic rocks and hornblende-biotite diorite).
Generating Indonesian-wide Vs30 Map Using Engineering Geomorphology Approach Cipta, Athanasius
Indonesian Journal on Geoscience Vol. 12 No. 2 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.2.217-229

Abstract

Earthquake hazards can be viewed from two perspectives, the first, source of earthquake and the second, place where we human live and carry out our activities. From the second point of view, information regarding the physical properties of soil where we are sitting on becomes crucial to calculate its vulnerability. Physical properties of soil, geologist calls it rock, are often represented by a single value, namely Vs30, which stand for average shear-wave velocity on the 30 m uppermost of soil. Measure Vs30 for whole country is a job with next-to-zero-possibility to complete, consequently, we need to have a technique to accurately estimate Vs30. Engineering gemorphology, a method that utilizes geology, and morphology to approximate Vs30 in national-scale level has been applied to create robust Vs30 data set for whole Indonesian region. Furthermore, the Mean Absolute Percentage Error (MAPE) is employed to judge the accuracy of the Vs30 produced from engineering geomorphology technique for Jakarta dan Jayapura data sets. According to MAPE score, which are 28.16% and 37.83%, engineering geomorphology is able to produce reasonable Vs30. If we split MAPE’s calculation into soil class of E, and D, in Jakarta the value is 39.63% (reasonable) and 24.75% (reasonable), while in Jayapura the MAPE score for E-, D- and C-classes are 74.22% (inaccurate), 40.09% (reasonable) and 24.00% (reasonable), respectively.

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