Journal of Geoscience, Engineering, Environment, and Technology
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Seismic Vulnerability Analysis Using the Horizontal to Vertical Spectral Ratio (HVSR) Method on the West Palu Bay Coastline
Full text linkThis research was carried out to make a map of the dominant frequency (f0), amplification factor (A0), seismic susceptibility index (Kg), Vs30, Sediment Layer Thickness (H) and Peak ground acceleration (PGA). Microtremor measurements were carried out with a three-component seismometer of the TDL-303S type as many as 27 measurement points. The data was analyzed by the Horizontal to Vertical Spectral Ratio (HVSR) method. The PGA calculation was carried out using the Kanai equation with a reference to the Palu-Donggala earthquake on September 28, 2018. The results showed that the distribution of the dominant frequency value (f0) ranged from 0.4149 Hz-0.8869 Hz, the soil amplification factor (A0) ranged from 2,199–4,884, the seismic vulnerability index (Kg) ranged from 8.79 s2/cm-41.41 s2/cm, the shear wave velocity to a depth of 30 meters ( Vs30) ranged from Vs30 197.7 m/s-320.2 m/s , the thickness of the sedimentary layer ranges from 260.3 m-291.1 m and the peak ground acceleration (PGA) of Kanai ranges from 137.3 gal – 234.2 gal by using Mw 7.4 earthquakes with an intensity scale (MMI) VI to VII. The coastal area of West Palu bay has an intermediate seismic vulnerability II to a high seismic vulnerability IV so that it will be vulnerable in the event of an earthquake disaster. Areas that have a very high vulnerability index are in the upper western and easternmost regions while those with a lower level tend to have a lower vulnerability index value
Impact of Land Use Change on Land Capability in Katingan Regency, Central Kalimantan, Indonesia
Full text linkThe imbalance between land use and land capability can cause environmental problems in Katingan Regency. This study aims to analyze changes in land use change for the 2015-2021 period, land capability, land cover suitability with land capability in Katingan Regency. This research uses the method of overlaying the 2015 and 2021 land cover maps, analyzing land capability with variables of erosion maps, flood maps, and aridity maps, and analyzing land suitability by overlapping land use maps and land capability maps. The results show that land use change is 67.864 ha with map accuracy KA = 90.6% and OA 81.1%, while the concentration of land use change in Malan Island District with an LQ value of 2.5. Land capability is divided into three with the limiting factors of erosion, flooding, and slope class, namely: class II, III, IV, VI, and VII which are designated as productive paddy fields, dry land agriculture, and agriculture mixed with shrubs. Land use change has an impact on land capability, namely the increase of unsuitable land by 23.050 ha. This research can provide important information for taking policies and strategies for optimizing land use at the site level in Katingan Regency in the future. 
Geological and Morphometric Characteristics of Quaternary Pyroclastic Aquifers in Salak and Pangrango Stratovolcano.
Full text linkIndonesia is located in a subduction zone formed by the collision of continental and oceanic plates. Many volcanoes form as a result of these conditions along the arc. Springs on the volcano's slopes are widely used for domestic, irrigation, and industry water use. Investigating the characteristics of aquifers and springs is essential to ensure groundwater sustainability by providing a robust geological framework. Meanwhile, groundwater in a volcanic geological setting has good quality characteristics because of its occurrence process, which interacts with many minerals in pyroclastic rocks that act as aquifers. The study area is located in the Lido Catchment Area (LCA), which is situated between two distinct volcanic slopes. Geological and morphometric analysis at LCA is the basis of important information relating to its hydrogeological systems. The analysis of thin rock sections and parameters of the physical properties of water in groundwater springs supports our research. We applied a comprehensive geological and morphometric analysis to obtain detailed information about the aquifer. This study aimed to determine the characteristics of aquifers in pyroclastic rocks and their relationship to the formation of springs. From the research conducted, the characteristic of water can be distinguished based on the geological conditions of its constituents. There are 6 different lithological characteristics in the study area: polymictic breccia, monomictic breccia, lapilli, lapilli tuff, coarse tuff, and fine tuff. From the lithology variations obtained, breccia, lapilli, and coarse tuff can play a good role as aquifers. Geological correlations and groundwater systems in the study area show groups of superficial, mixed, and alteration springs. The system of water flows in aquifers through inter-grains or rock fractures. The types of springs in LCA are dominated by depression and fracture types. These results are fundamental information for understanding hydrogeological systems in future volcanic geological settings
Analysis The Effect Of Column Height Variation On The Perfomance Of Increased Building Structure
Full text linkThe consequences of these earthquake waves cause damage to buildings ranging from light damage to heavy damage. Dealing with the case, it is necessary to plan and implement earthquake-resistant building structures, especially in high-rise buildings. Another factor that needs to be considered is the function of the room which affects the column height when the column height is different and it causes uneven stiffness from the ground floor to the top.
The aim of this study was to find out the effect of variations in column height on the performance of multi-storey building structures in terms of shear forces, floor drift and buckling load (Pc). The method used in this study was the response spectrum method. The spectrum response is the maximum response of a Single Degree of Freedom (SDOF) structural system, both acceleration, velocity and displacement due to the structure being loaded by a certain external force. Before carrying out the analysis using the response spectrum method, a structural model was undertaken by varying the column height on the 1st floor into 3 variations.
Dealing with the results of the analysis on the building structure model with varying column height on the 1st floor, it indicated that the higher the column the maximum base shear force value increases. The higher the 1st floor column, the maximum floor deviation value increases. The higher the column the value of the column slenderness ratio increases and the Euler buckling load decreases
Petrography and Geochemistry for Proposal of Geodynamic Model For The Irbiben Granite in Tagragra d’Akka inlier, (western Anti-Atlas, Morocco)
Full text linkThis study aims to contribute to improve the knowledge on the setting of the Irbiben granites, located south of the gold deposit of this locality (Tagragra d'Akka buttonhole, Anti-Atlas, Morocco). The petrographic characterization showed leucocratic porphyry rocks, with a mineralogy dominated by quartz and phenocrysts of plagioclase, alkali feldspars of sometimes centimetric size as well as very small sulphides of metallic luster. Two generations of quartz have been identified: a QIquartz with undulating extinction phenocrysts testifying to an episode of deformation orchestrated in this inlier, and a QII quartz with more rounded and limpid minerals indicating an intense silicification. Plagioclase and alkali feldspars are deeply altered to sericite and epidote. Geochemical characterization classifies these rocks as calc-alkaline series granites, rich in potassium, with a peraluminous character indicating their crustal origin. Their arc geochemical signature, Ba enrichment, and negative Nb, Ti, and P anomalies are characteristic of a subduction zone. This subduction could be associated with an episode of convergence between an oceanic lithosphere located in the north and the West African craton in the south, as shown by the proposed geodynamic model
Economic Feasibility Analysis of Fishing Job Operation in Well YS13
Full text linkOil consumption in Indonesia has increased from year to year. However, the increasing demand for oil and natural gas is inversely proportional to oil and gas production, which always declines from year to year. One of the factors causing the decline in production is the well damage. Well YS13 is a well that is damaged in the form of fish in the well. A fishing job is the most appropriate option to solve the problem of the presence of fish in the well because the fish in the well must be removed to continue well production activities or drilling activities. This study aimed to determine the economic feasibility of fishing job activities to be carried out at the YS13 well. The research begins with the preparation of the required data, then calculate the predicted production of the YS13 well with the decline curve method, estimates the cost of the fishing job, and economic fishing time (EFT). And determines the economic feasibility of the fishing job project by calculating profit indicators, namely Net Present Value (NPV), Internal Rate of Return (IRR), and Pay Out Time (POT). The results of calculations using the decline curve method obtained that the total production for 20 months is 4293.52 bbl. The EFT value is 3 days with Ps = 10% and the total cost of fishing is 147.367,20, IRR = 114%, and POT = 1.44. From the results of the calculation of the economic feasibility, the project is considered feasible to be carried out
A Comparison of Geologic Structure Detection of Sumatera Island Using Goce Satellite Gravity Data and Sgg-Ugm-2 Data
Full text linkGOCE gravity satellite data can be used for regional fault detection because the observation area is wide and not limited by area. In this study, GOCE satellite data is used to detect geological structures on the island of Sumatra, the results of which are used as the basis for disaster mitigation. GOCE data and SGG-UGM-2 were processed using the GOCE User Toolbox (GUT) software to produce a gravity disturbance map and a complete bouguer anomaly map. The GOCE obtained results were validated using the SGG-UGM-2 high-resolution gravity model data. The calculation results obtained that the gravity disturbance value from the GOCE data was around -140 to 200 mGal, while the value of the gravity disturbance from the SGG-UGM-2 data was around -180-300 mGal. The GOCE gravity disturbance map and the SGG-UGM-2 can detect the Subduction Trench, Mentawai Fault, and West Andaman Fault on Sumatra Island with negative values, while the Sumatran Fault Zone (SFZ) along Sumatra Island with positive values in line with the presence of mountain ranges. The results of the SGG-UGM-2 data processing for the gravity disturbance are more detailed than GOCE because the SGG-UGM-2 data degree is higher than that of GOCE. GOCE complete bouguer anomaly value is around 40-560 mGal, while the value of complete bouguer anomaly SGG-UGM-2 is around 60-560 mGal. The complete bouguer anomaly maps from GOCE and SGG-UGM-2 can detect patterns from the Subduction Trench, Mentawai Fault, and West Andaman Fault but cannot clearly detect SFZ. The complete bouguer anomaly can also detect differences between oceanic and continental crust. The GOCE and the SGG-UGM-2 complete bouguer anomaly map show almost similar patterns and the ability to detect geological structures for sub and regional Sumatra Island. In addition, GOCE data detect geological structures more clearly than GRACE data