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EAGE-HAGI 1st Asia Pacific Meeting on Near Surface Geoscience and Engineering
- Conference date: April 9-13, 2018
- Location: Yogyakarta, Indonesia
- Published: 09 April 2018
41 - 60 of 115 results
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Seismic Lahar Characteristics of Merapi Volcano Post 2010 Eruption
Authors Sulistiyani, IGM. A. Nandaka and NurudinSummaryMerapi 2010 eruption ejected at least 130 million m3 volcanic material, mostly enter to Gendol River. More than 100 lahar events were generated around Merapi. Lahar at Merapi triggered by the rain intensity occurred at the summit. BPPTKG built the lahar flow monitoring station in order to mitigate the lahar disaster. The intention was to give early warning to the society. Lahar flows monitored using non-contact detection instrumentations installed near the rivers. These devices were geophones and IP-based camera.
This paper will present the seismic lahar characteristics recorded at Kali Gendol station. Events recorded on February 21, 28, April 23, 24 and also May 1, 2011, has been analyzed to know the characteristics. Most of the data had saturated amplitude due to the big magnitude lahar caused by the blocky materials. Seismic signal shows that the flow can be differentiated into single-pulse and multi-pulse events. Dominant frequency before the arriving of the lahar was fluctuating because of the human activity, traffic, etc., while the body of the lahar was 8–18 Hz. Maximum amplitude ranged between 1x104 – 1.9x104 Count (saturated). By knowing these lahar characteristics, amplitude and frequency result can also be used to refining the lahar early warning system.
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Hypocenters Relocation Using Double Difference Method Around Mount Agung, Bali
Authors E. Ulfiana and R. M. SipayungSummaryAfter a long sleep for 54 years, now we are surprised by the presence of seismic activities of Mount Agung that has recorded since September 2017. We can’t prevent the eruption, however we can observe magma movement in the body of volcanos. Hypocenters distribution is an important information that can be used to reveal the magma movement in the body of volcano. For a more accurate hypocenter, we did relocation of earthquake hypocenter that has occured in Mount Agung area, periode September–November 2017 (Catalog data from BMKG). We used Double Difference method that compute in HypoDD program. We success relocated 331 from 415 events that occured since September-November 2017 in Mount Agung area. The hypocenter distribution looks more accurate and earthquakes are located under Mount Agung with range depths 3–42 km. The dominant hypocenter distribution lies to the southwest of Mount Agung, ie toward the middle between Mount Agung and Mount Batur. Magma is going move toward the surface or in brittle zones of Mount Agung. The small eruption has occured in Mount Agung, so we expected a higher probabilty for a large eruption can be occure following these small eruptions.
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Spectra analysis for source dynamic identification of deep volcano tectonic underneath mounth Sinabung, North Sumatera
Authors K. Brotopuspito, T. Kusmita and H. TriastutySummarySpectra frequency of VT indicates the effective stress of volcanic activity. Spectra frequency of VT indicates the effective stress of volcanic activity. These spectra parameters could be applied to determine source and the dynamics of the source of the VT earthquake. This study analyzed the spectra VTA earthquake in the Sinabung volcano between July and November 2013, by applying the FFT algorithm based on the Brune model. Analysis show that the corner frequency of VTA earthquakes of Sinabung volcano were dominated by frequency of 12 – 13 Hz. Hypocenter positions were at a depth of 2 km - 20 km from the summit. Epicenter positions were spread towards the Northwest from the summit, i.e to the Lake Kawar direction. Most of the VTA source mechanisms are strike slip and oblique, and small portion of normal faults and reverse faults. Energy accumulation before the eruption was occurred from July to August and after eruptions in October. On this October accompanied by the formation of a new dome and followed by a magmatic eruption in November. Fractures that triggered the eruption was happened on September 12nd, 2013 and ended on September 22nd.
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Identification of Distribution and Calculation of Manganese Reserves from VLF and IP Method in Pengasih, Yogyakarta
More LessSummaryResearch about manganese reserves has been done in the Karangsari Village, Pengasih District, Kulonprogo Special Region of Yogyakarta. Explorations and exploitation of manganese has been done by local community using traditional method. This research aims to determine the condition of subsurface, manganese distribution, and the amount of manganese reserve in research area. The method used is VLF method and IP method. The line of VLF measurement is 6 line with 300 m length. IP line using dipole-dipole configuration has 5 lines and 300 m length, spacing between electrode 20 m and number n 8. The aquisition using T-VLF BGRM IRISH instrument and Syscal Jr. Resistivity meter. The result of the research is the distribution of manganese in resistivity< 40 ohm.m and chargeability< 10 msec. The range is used for 3D modeling and manganese volume of 228,000 m3. The manganese reserve of the research area is 984,960 ton
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3D ERT/IP Imaging for Sulfide Mineralization over Proterozoic metavolcanics in Dhanjori Basin, Eastern Singhbhum, India
Authors A. K. Gupta, S. Srivastava and R. K. SinghSummaryThe study area, Paleoproterozoic metavolcanics in Dhanjori Basin, Eastern Singhbhum, India, is the rich source of gold associated with sulfide, quartzite veins and Quartz Pebble Conglomerate. ICP-AES analysis of samples from the study area reported the average concentration of gold, silver, copper, uranium, magnetite, lead and zinc as 5ppm, trace, 110 ppm, 50 ppm, 1.5 ppm, 6.5 ppm and 55 ppm respectively. A regional audiomagnetotellurics (AMT) study in the region indicated the presence of shallow conducting heterogeneities. This study presents the results of 3D Electrical resistivity tomography (ERT)/Induced Polarization (IP) surveys for detection of sulfide mineralization over one of these conductors identified from AMT study. The inverted model shows conducting and moderately chargeable zone as a weathered cover shallow aquifers up to 20 m depth. However, for depths more than 20 m, the lithology is broadly resistive with few conductors of small dimensions surrounding it. These are distinguished on the basis of chargeability variations from low (6mV/V) to high (90 mV/V) indicating distinct geological features such as massive sulfide, QPC/quartz vein with disseminated sulfide gold, greenstone schist, and dolerite dike/Proterozoic gabbro anorthosite mass. The future scout drilling program has been concentrated on the identified zones of sulfide mineralization.
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Manganese Mineral Exploration in Kulon Progo District Using Induced Polarisation Method
Authors G. Erlangga, I. Arifianto and K. AfafaSummaryKliripan and Anjir Sub-village, Kulon Progo district were known as one of big manganese mining in Java island, but a big scale mining on the surface is uneconomic anymore. Based on the geological setting, there is a chance to discover a new deposit resource in the subsurface. Therefore, manganese exploration using induced polarisation method had been done in this area. Data acquisition was obtained by utilizing Syscal Jr. with 10 – 20 meter electrode spacing, and n=6. The data was processed to delineate a prospect zone of manganese mineralisation. Resistivity and chargeability of manganese are considered in the interpretation. Mineralisation zones of manganese are clearly seen at the second and third line. From the reference, manganese minerals have a 135 – 250 msec chargeability value. On the second line, the mineralized zone is located at 65 meters above sea level and distance of 250 meters on section line. While mineralisation zone in the third line is located at 70 meters above sea level and a distance of 110 meters on the section line, both of them are at Anjir Sub-village. The mineralisation zone is guessed potential as a manganese hill associate with limestone deposit, refer to the outcrop at surface.
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Remote Sensing Application in Exploration of Iron Mineral Placer Deposit: Case Study of Kulonprogo’s Iron Placer Deposit
Authors I. D. Putra, R. Abbas, S. D. Masti and I. W. WarmadaSummaryIndonesia is a country of Island arcs setting, tectonically. This setting has induced many of volcanoes Indonesia followed by the presence of mineral deposits. As the consequences of never-ending demand for ore minerals, exploration of mineral deposits are always needed. The study area is located in Kulonprogo, Yogyakarta. The study area is marked by secondary type mineral deposit presence of Placer type. Several band combinations analysis of Landsat 8 OLI/ TIRS 432, 567, and rationing of band 5/6 and 4/2 are done as methods in order to reveal the geological, and geomorphological conditions of the study area and the dissemination of iron-bearing mineral in the source and in the secondary deposit. The result of the analysis is the dissemination of the iron-bearing mineral are present covered wide area within and around the Glagah beach, the iron mineral source are located several kilometers to the north, the transportation of iron-bearing mineral is done through fluvial mechanisms of Serang and the other River to the beaches in the south. Some factors are also expected to affect the deposition processes, such as mineral density, waves, and river’s current speed. From this study, it’s believed that remote sensing is useful “tool” in mineral exploration.
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The Potential Development of Rajabasa Geothermal Manifestations in Kalianda Into Geoturism Area in South Lampung
Authors M. Addiansyah, R.D. Linggadipura, A. Krestanu and M.H. PrasetyoSummaryKalianda has very interesting geological phenomena that evidenced by the existence a several manifestations of Mount Rajabasa Geothermal System those became the research object of geoturism area development. The research methods are field observation, studio analysis, and quantitative analysis of geosite and geomorphosite based on Kubalikova (2013 ) to assess the development potential of Kalianda into geoturism area. Parameters of quantitative analysis of geosite and geomorphosite that used are scientific and intrinsic value, educational value, economic value, conservation value, and additional value. Based on the results of field observation and quantitative assessment towards geological objects located in Kalianda and surrounding area, six geological objects that are potential to become geosites and geomorphosite. Those are Rajabasa Volcanic 65.1%, Maribung Waterfall 46.6%, Way Kunjir Geyser and Hot Spring 45.9%, Wartawan Beach 72.5%, Belerang Simpur Hot Spring 66.6%, and Way Belerang Hot Spring 65.2%. Those data indicate that Kalianda Area has potential to become geotourism area geoscience field campus with volcanology, geothermal, and oceanography learning aspects. In order to optimize the operational geoturism area needs to be equipped with cleanliness facilities, lodging, and scientific sign board. Kalianda Geoturism Area development is believed will improve the economy of the community around Kalianda Area.
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Estimation of average electromagnetic wave velocity in tree trunks for the reflection imaging by GPR
Authors K. Takahashi and K. AoikeSummaryWe developed a simple method to estimate average propagation velocity of electromagnetic waves in tree trunks. The method employs GPR transmission measurements that fixes the transmitting antenna and scans receiving antenna circumferentially on the perimeter of a trunk. The data exhibit an arrival time curve since the measurement configuration consists of various propagation lengths. We modified the velocity analysis of CMP measurement and calculate semblance as a function of relative permittivity (or velocity). The maximum semblance indicates the permittivity value that best describes the arrival time curve in the transmission data and the value is the estimation. We demonstrate the method with a laboratory experiment with a drilled log and that the estimated permittivity gives better reflection image than other values.
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Earth Material as Supporting Tool in Legal Case Investigation and the Role of Geoscientist in Disclosing the Criminal
More LessSummaryForensic geology is defined as the application of earth science in the field of law (Munroe, 2002). Forensic geology to date still sounds foreign, especially in Indonesia. Whereas the application of forensic geology can be a reinforcement tool in law enforcement processes. The background of the use of earth’s material as an instrument of investigation is the variety of materials of this earth, such as soil, lithology, minerals, fossils. The diversity ranging from physical, biological to chemical, such as size, color, shape, composition, and mineralogy. In this modern era, tools have been able to identify such materials as using polarization microscopes for microscopic observation. Another thing that underlies the application of forensic geology is the assumption that any contact with the earth’s material will result in a trace of the perpetrator, the victim, the object, or the scene of the case which then identified the material, its origin, similarities with other areas, and so on. This becomes a great potential in the law enforcement process, and becomes a supporting tool to unravel the mystery of the criminals. Here the geoscientist’s role is needed to identify and observe the earth’s material and Indonesia has many reliable geoscientist to solve the problem.
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Merangin Paleobotany Park: Geological Aspects and Characteristics
More LessSummaryIndonesia with its complex tectonic structure are gifted by abundant resources spreading along its archipelagos in both biological and geological resources, in terms of landscapes, fossils, rocks, and other geological aspects. Geopark as a product of these setup are now intensively developed in Indonesia as well as other countries. One of well-known geoparks in Indonesia is Merangin Geopark that administratively located in four regencies, including Merangin Regency, Kerinci, Sarolangun, and West Tanjung Jabung. This geopark is mostly acknowledged for its finding fossils and geological landscapes that have a high scientific value in terms of geology for scholars interested in studies related to the earth formation history for education and research purposes. Focusing in geological condition of Merangin Paelobotany Park as a core region of Geopark Merangin, this study can be utilized as a comprehensive study to enlarge the references regarding the geological condition in this study area. There are at least 18 geosites available in this area, consists of diverse morphology, such as lakes, caves, rivers, underground rivers, waterfalls, and mountain; unique geological structures; variety of rock types; and Araucarioxylon wood fossil as the icon of Merangin Geopark with other various fossils - plant roots, trunks, leaves, and marine animals.
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Conductivity-depth imaging of semi-airborne transient electromagnetic data
Authors X. B. Wang and X. D. YuSummaryConductivity-depth imaging is a common method for the interpretation of airborne transient electromagnetic data. The interpretation of Semi-airborne transient electromagnetic data is similar to the airborne transient electromagnetic method, due to the large amount of data, the similar imaging method is also required. In this paper we present a SATEM CDI method which based on nonlinear implicit function, and use one field data to verify the practicability of this method, and we also compared the CDI results with the geological information and ground inversion results. The results demonstrate that this CDI method is practical for SATEM data.
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Magnetotelluric 1D Inversion Using Grid-Search and Monte Carlo Methods
Authors S. Maulinadya and H. GrandisSummaryThe magnetotelluric (MT) 1D inversion modeling is relatively simple and can be considered as a solved problem. Nevertheless, this subject still attracts researchers to study further for its nonlinearity, equivalence and usefulness for particular situation. For example, in the preliminary stage of a geothermal exploration program, 1D MT modeling is still employed to obtain an overall view of the subsurface resistivity distribution in the prospect area. Another example is the regional study of basement structures where the filling sediments are mostly stratified. From the
computational point of view, the nonlinear, gradient-free approaches to the inverse problems are gaining interest due to the availability of powerful computational resources. The paper describes the 1D MT inverse problem resolution using grid-search and Monte Carlo approach. The “a priori” information is set to define the model space or search area. The grid-search attempts to search for the solution by evaluation of all possible models contained in the model space. The Monte Carlo approach is used to reduce the execution time using random samples from the model space. Tests
using synthetic and field data associated with simple synthetic models showed satisfactory results, in terms of model recovery and misfit.
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Near surface passive seismic HVSR surveying for mineral exploration, regolith mapping and other applications
Authors D. Stannard and J. MeyersSummaryA presentation highlighting the application of the HVSR passive seismic technique to assist with regolith and basin thickness mapping for exploration of mineral deposits, shallow sedimentary basin mapping and shallow quarry materials. Several case studies from passive seismic surveys carried out by Resource Potentials using the Tromino seismometers will be presented to highlight some of the potential applications of this technique for widespread exploration throughout Indonesia and SE Asia.
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IP-Resistivity for shallow gold exploration. Case Study: “UBITS” block, Pohuwato District, Gorontalo Province.
Authors V. A. Prasetyo, P.R. Aripin, A. Ismanto and M. E. C. LubisSummaryIP-Resistivity method has been conducted for shallow gold exploration in UBITS block, Pohuwato District, Gorontalo Province. The occurence of gold mineralization linked to low sulphidation system. From the 2D section the high chargeability and high resistivity are the two vectors for gold mineralization zone.
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Investigation of the Structural Controlled Mineralization: Integrated Geology, Geophysics and Remote Sensing in Kulonprogo
Authors B. B. Prabowo, V. P. Harefa, S. E. Senduk, A. A. E. Wowor, Y. D. Tae and R. R. SeranSummaryThe Kuloprogo high is also a fairly complex area of alteration and mineralization. A study of geological structures at Kulonprogo high was conducted to determine the structural control of alteration and mineralization and further investigation of the potential availability of valuable metal minerals in the area. The study was conducted with alignment interpretation through Remote Sensing Geology, Geophysics and measurement of geological structure data.
In the result of the research. The presence of the mineralization is controlled by two tectonic phases that develop in the area. This is evidenced from geological mapping and alteration where the acquisition of mineral alterations that characterize the presence of mineralization. Hydrothermal alteration in the research area is silicification, argillic and prophylitic. Based on the characteristics of alteration and mineralization, the study area is included in low sulfidation epithermal type. It also appears on the Remote Sensing results where the targeted mineral distribution to be searched shows the distribution patterns trending to the structures geology that develop in the area. And from geophysical data showing a destructive magnetite pattern following along the structural zone as an accumulated container of gold and base metal.
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Characterization of Microtremor for The Identification of Subsurface Rivers at Kedung Banteng, Pacitan, Indonesia
Authors P. Chemistra, A. S. Bahri, W. Utama and A. WidodoSummaryHas been conducted research of microtremor characterization based on analysis of curves HVSR, particle motion, and time frequency analysis at Kedung Banteng river system, Pacitan, East Java, Indonesia to identify subsurface rivers using these characters. From particle motion data processing on 12 points of microtremor measurements, in area I, which is a river area, the resultant direction of point TA8, TA9, TA10, and TA13 is NW-SE due to the position of points that is parallel to the stream flow with E-W direction. It can be concluded two things. First, river can be the source of vibration to the point of measurement. Second, direction of particle is perpendicular to the direction of river flow.
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Utilizing Oil and Gas Industry Data to Understand Deeply Tarakan Earthquake
Authors H. Indrajaya, T.K. Usman and S. NuratmajaSummaryDuring this time people consider that the island of Kalimantan is a relatively safe area of the earthquake, but in fact it is not. One example is the earthquake that occurred in Tarakan. It happens in 2015 and 2017. Losses in the form of seven homes damaged but no casualties. The Tarakan region is located in North Kalimantan where the region is located in a compression zone caused by the Mangkalihat and Sampoerna Faults movement resulting in a wrench fault system. Given the data commonly used by Pertamina EP in constructing a subsurface model in oil and gas discovery combined with earthquake data it is hoped it will be easier to understand Tarakan earthquake which has been going on for two years. Three things will be examined in this paper to understand the characteristics of the Tarakan earthquake, which are earthquake active faults, the type of lithology surrounding epicenter earthquakes, and high stress areas.
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Determining Groundwater Recharge Potential Zone in Yogyakarta: Remote Sensing and GIS Approach
Authors A.S. Banuzaki, L.H.K. Pratiwi, G. Ikhwanushova and A. SetiantoSummaryYogyakarta is one of most-populated provinces in Indonesia having a high groundwater utilization. Most of water usages are still derived from groundwater resource. This condition is exacerbated by urbanization process which has a big deal on decreasing recharge area of groundwater due to land use change. To understand the water balance and the vulnerability of groundwater in Yogyakarta, the recharge area of groundwater need to be analyzed. The quantifying of recharge potential zone in Yogyakarta, was conducted by the integration of all factors influencing the hydrogeological process, those are lithology, land cover/land use, lineament and drainage frequency density, and geomorphology. The data were gained from satellite images (DEM and Landsat 8) and other exogenetic data (geomorphologic and geologic map). A GIS approach was used to integrate each influencing factor which has its own degree of effect. The groundwater recharge potential zone in Yogyakarta is well estimated using this method.
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Comparison of Transient Electromagnetic and DC Resistivity for aquifer layer in Cisarua, Bandung Barat Regency
Authors A. Laesanpura, D. Dahrin, W. Warsa, W.W. Parnadi, D. Abdurrahman, I.B.S Yogi and R. MarthenSummaryGeophysical investigation is conducted to study groundwater in water absorption region for Bandung Basin hydrology system. It is placed in Cisarua, Bandung Barat Regency, which composed of old and young volcanic products. Resistivity based geophysical methods are used, Geoelectrical Resistivity and Transient Electromagnetic (TEM). TEM measurement are usingused long grounded wire configuration with transmitter length 500 m and current 13 A. Geoelectrical Resistivity are usingused Wenner-Schlumberger configuration with maximum array distance 560 m. TEM Measurement recorded high amount of cultural noise since it is was near to cellular and radio transmitters. After filtering and inversion process, low resistivity zone (35–40 Ωm) are were detected at elevation 1185–1075 m. Deeper low resistivity zone assumed to have high water saturation are were also detected at 210 – -290m. This resultsed are were correspond with Geoelectrical Resistivity measurement which detecteddetect low resistivity zone at 1185 – 1140 m, with lowest resistivity value was 32 Ωm. In Geoelectrical Resistivity Section, we can could see that the low resistivity zone is was continuous from north to south. From both methods, the low resistivity zone are were interpreted as shallow unconfined aquifer serve as water source for domestic well in study zone.
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