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Geological Engineering Departement Universitas Gadjah Mada Jl. Grafika No. 2 Kampus UGM Yogyakarta 55281 Phone +62-274-513668 Fax +62-274-546039
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Journal of Applied Geology
ISSN : 25022822     EISSN : 25022822     DOI : https://doi.org/10.22146
Journal of Applied Geology – JAG focuses on the applied geology and geosciences with its key objective particularly emphasis on application of basic geological knowledge for addressing environmental, engineering, and geo-hazards problems. The subject covers variety of topics including geodynamics, sedimentology and stratigraphy, volcanology, engineering geology, environmental geology, hydrogeology, geo-hazard and mitigation, mineral resources, energy resources, medical geology, geo-archaeology, as well as applied geophysics and geodesy.
Articles 6 Documents
Search results for , issue "Vol 6, No 2 (2021)" : 6 Documents clear
Numerical Analysis of Slope Stability Due to Excavation of Diversion Tunnel at Pamukkulu Dam Site, Indonesia Wakhid Khoiron Nugroho; I Gde Budi Indrawan, Dr.; Nugroho Imam Setiawan
Journal of Applied Geology Vol 6, No 2 (2021)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (7466.289 KB) | DOI: 10.22146/jag.57658

Abstract

Located in the Takalar Regency of South Sulawesi Province, the Pamukkulu Dam is planned to use a tunnel type as its diversion structure. One of the critical parts in the tunnel construction is the stability of portal slopes. This research aimed to estimate the effect of tunnel excavation on the stability of the portal inlet and outlet slopes under static and earthquake loads by using the finite element method. The slope stability analyses were carried out under conditions of prior to and after tunnel excavation. The input parameters used were laboratory test results in the forms of index properties and mechanical properties taken from rock core drilling samples, completed with the rock mass quality parameters based on the Geological Strength Index (GSI) classification. The Mohr-Coulomb failure criterion was used to model strength of the soil, while the Generalized Hoek-Brown failure criterion was used to model strength of the rocks. The results of rock cores analysis using the GSI method showed that the inlet tunnel slope consisted of four types of materials, namely residual soil, fair quality of basalt lava, good quality of basalt lava, and very good quality of basalt lava. Meanwhile, the outlet portal slope consisted of three types of materials, namely residual soil, good quality basalt lava, and very good quality basalt lava. The calculated horizontal seismic coefficient for the pseudo-static slope stability analysis was 0.0375. The analysis results of slope stability in the Y1 inlet section had a critical Strength Reduction Factor (SRF) value of 2.35 in a condition prior to the tunnel excavation and a critical SRF value of 2.34 after the tunnel excavation. The Y2 outlet section had a critical SRF value of 13.27 in a condition before tunnel excavation and a critical SRF value of 5.55 after the tunnel excavation. The earthquake load addition at the Y1 inlet section showed a critical SRF value of 2.05, both before and after the tunnel excavation. The Y2 outlet section showed a critical SRF value of 11.49 before the tunnel excavation and a critical SRF value of 5.54 after the tunnel excavation. The numerical analysis results showed that earthquake load reduced critical SRF values of the slopes. At the Y1 inlet section, the tunnel excavation did not have a significant effect on slope stability. It was demonstrated by an extremely small decrease in a critical SRF value of 0.43% for a condition without an earthquake load and an unchanged critical SRF in a condition with an earthquake load. At the Y2 outlet section, the tunnel excavation had a more significant effect on the slope stability. It was exhibited by the decrease in the critical SRF value of 58.18% in a condition without an earthquake load and a decrease in the critical SRF value of 51.78% in a condition with an addition of an earthquake load. However, the analysis of slope stability for both sections showed that all design slopes were above the required allowable safety factor value.
The Engineering Characteristics and Classifications of Rock Masses along Road Section from Prambanan to Patuk, Yogyakarta, Indonesia Aisyah Shahirah Juhari; I Gde Budi Indrawan, Dr.; Wahyu Wilopo
Journal of Applied Geology Vol 6, No 2 (2021)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (4973.159 KB) | DOI: 10.22146/jag.58034

Abstract

Several attraction places and agriculture area that essentials for tourism and villager to do their activities are located approximately 6 km along the road of Candi Ijo to Ngoro-Oro in between Prambanan and Patuk sub-districts, Yogyakarta, Indonesia. Many jointed rock masses along the road have the potential to fail. This paper describes the rock mass characteristic and quality determined using the Geological Strength Index (GSI) and Rock Mass Rating (RMR) classifications. The rock mass characteristic and quality were essentially the preliminary results of a study to evaluate stability of the rock slopes along the road of Candi Ijo to Ngoro-Oro. Field observation and laboratory tests were carried out to determine parameters of the GSI and RMR.  The results show that the slopes in the study area consisted of tuffaceous sandstone, vitric tuff, lithic tuff, cemented tuffaceous sandstone, lapilli tuff, subarkose, laminated mudrock, and laminated tuffaceous sandstone. The intact rocks were classified as weak to very strong. The research area consisted of three rock mass qualities, namely fair rock mass quality having GSI between 30 and 45 and RMR between 41 and 60,  good rock mass quality having GSI between 46 to 65 and RMR between 61 and 80, and very good rock mass quality having GSI > 65 and RMR between 81-100. The relationship between GSI and RMR obtained in this study was in good agreement with that proposed by Hoek et al. (1995).
Evaluating the Implications of Lineaments on Petroleum Fields: South Sumatra, Indonesia Tapiwa Frank Kwachara Ngoroyemoto
Journal of Applied Geology Vol 6, No 2 (2021)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1454.759 KB) | DOI: 10.22146/jag.58161

Abstract

Declining oil prices has led to a reduction of petroleum exploration as oil production as no longer a lucrative area of investment as in the previous years. Current exploration activities are supported by field work which are intensive considering the resources required. There is need to develop low cost methods to delineate areas of potential hydrocarbon resources. This research uses Land Satellite (Landsat) 8 Operational Land Imager (OLI) for alteration extraction, Shutter Radar Topography Mission (SRTM) for lineament extraction, Geological maps to develop a low cost method of petroleum exploration. The results indicate high OH bearing alterations on the Gumai and Kasai formation, a seal rock. Extensional tectonics is responsible for the migration of petroleum from the subsurface.  It is suggested that future exploration be concentrated on the Gumai and Kasai formation based on evidence of micro seepage.
Landslide Susceptibility Mapping and Their Rainfall Thresholds Model in Tinalah Watershed, Kulon Progo District, Yogyakarta Special Region, Indonesia Thema Arrisaldi; Wahyu Wilopo; Teuku Faisal Fathani
Journal of Applied Geology Vol 6, No 2 (2021)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1320.544 KB) | DOI: 10.22146/jag.59185

Abstract

Landslide often occurred in Tinalah watershed, Kulon Progo District, every year. The frequency of landslide events is increasing after high rainfall intensity. Some factors control landslides such as slope gradient, land use, geological structure, slope hydrology, and geological condition. This research has an objective to develop the susceptibility map of Tinalah watershed and to identify the rainfall threshold to trigger a landslide. The development of the susceptibility map using frequency ratio method with four parameters including slope, type of rock, land use, and lineament density. The landslide data were collected during the field survey and from regional disaster management authority (BPBD) Kulon Progo. Rainfall data were collected from BMKG and GSMap. Soil analysis also was conducted to develop a numerical model to verify the rainfall threshold value. The result shows a high susceptibility of the landslide area is dominated in Tinalah watershed. The rainfall threshold for the low susceptibility of the landslide zone is I=490.14 D-1.404with 5-7 days antecedent rain. The rainfall threshold for medium susceptibility map is I=164.32D-0,689 3-7 days antecedent rain. Moreover, the rainfall threshold for the high susceptibility of the landslide zone is 111.62 D-0.779, with 2-7 days antecedent rain.
Comparison of Different Multispectral Images to Map Hydrothermal Alteration Zones in Kokap, Kulon Progo Bayu Raharja; Agung Setianto; Anastasia Dewi Titisari
Journal of Applied Geology Vol 6, No 2 (2021)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2833.932 KB) | DOI: 10.22146/jag.60699

Abstract

Using remote sensing data for hydrothermal alteration mapping beside saving time and reducing  cost leads to increased accuracy. In this study, the result of multispectral remote sensing tehcniques has been compare for manifesting hydrothermal alteration in Kokap, Kulon Progo. Three multispectral images, including ASTER, Landsat 8, and Sentinel-2, were compared in order to find the highest overall accuracy using principle component analysis (PCA) and directed component analysis (DPC). Several subsets band combinations were used as PCA and DPC input to targeting the key mineral of alteration. Multispectral classification with the maximum likelihood algorithm was performed to map the alteration types based on training and testing data and followed by accuracy evaluation. Two alteration zones were succeeded to be mapped: argillic zone and propylitic zone. Results of these image classification techniques were compared with known alteration zones from previous study. DPC combination of band ratio images of 5:2 and 6:7 of Landsat 8 imagery yielded a classification accuracy of 56.4%, which was 5.05% and 10.13% higher than those of the ASTER and Sentinel-2 imagery. The used of DEM together with multispectral images was increase the accuracy of hydrothermal alteration mapping in the study area.
Assessment of heavy metal contamination in soil around Piyungan Landfill, Yogyakarta, Indonesia Mufid Muyassar; Wawan Budianta
Journal of Applied Geology Vol 6, No 2 (2021)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (530.069 KB) | DOI: 10.22146/jag.65651

Abstract

One of the negative impacts of the landfill as solid waste disposal is soil contamination by heavy metals. This study assessed heavy metals impact, especially Pb, Cu, Zn, and Cd, in the soil in Piyungan landfill, Bantul, Yogyakarta, Indonesia. The assessment was conducted by analyzing 15 soil samples from 25 cm depth in the study area, which was divided into three-zone. The study results showed that generally, the highest content of metals was found in zone II, which is located near or directly situated in a landfill site. The pollution index (PI) calculated showed in order Cd>Cu>Pb>Zn. The result also indicates that Cd has the highest pollution index and even the highest risk compared to Pb, Cu, and Zn. The eco-risk index (RI) calculation showed that the value was 29 to 70 demonstrating a low class. The result also indicates that the accumulation of heavy metals investigated in this study was normal, and that the ecological risk was relatively low.

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