• Title/Summary/Keyword: Geological Survey

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Resistivity Protecting analysis due to test survey result (시험탐사 결과에 따른 전기비저항 탐사 분석)

  • Kim, Jae-Hong;Hong, Won-Pho;Park, Chul-Sook;Im, En-Sang
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1285-1289
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    • 2008
  • Increasing the flood control capacity's link that is enforcing to existing dam by unusual change of weather, While build planing construction by exiting spillway of tunnel type to dam, could know that part bed rock is formed as is different with design. Grasped topography of research area and geology state to definite distribution aspect of different bed rock, Place that achieved Surface geological Survey and correct Survey is difficult in some section enforced Electrical resistivity dipole-dipole investigation. Grasped stratigraphy distribution confirmation and fracture or weathering zone making out siding 2D-Resistivity Electrical resistivity diagram and Reverse analysis diagram, examining closely soil weathered rock rock's distribution state, established stability countermeasure plan

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DEFORMATION OF AUGUSTINE VOLCANO, ALASKA, 1992-2006, MEASURED BY ERS AND ENVISAT SAR INTERFEROMETRY

  • Lee, Chang-Wook;Lu, Zhong;Kwoun, Oh-Ig
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.582-585
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    • 2006
  • Augustine volcano is an active stratovolcano located southwest of Anchorage, Alaska. Augustine volcano experienced seven significantly explosive eruptions in 1812, 1883, 1908, 1935, 1963, 1976, and 1986, and a minor eruption in January 2006. To measure ground surface deformation of Augustine volcano, we applied satellite radar interferometry with ERS-1/2 and ENVISAT SAR images acquired from three descending and three ascending satellite tracks. Multiple interferograms are stacked to reduce artifacts due to changes in atmospheric condition and retrieve temporal deformation sequence. For this, we used Least Square (LS) method for reducing atmospheric effects and Singular Value Decomposition (SVD) method for the retrieval of a temporal deformation sequence. Interferograms before 2006 eruption show about 3 cm/year subsidence by contraction of pyroclastic flow deposits from the 1986 eruption. Interferograms during 2006 eruption do not show significant deformation around volcano crater. Interferograms after 2006 eruption show again a several cm subsidence by compaction and contraction of pyroclastic flow deposits for a few months. This study demonstrates that satellite radar interferometry can monitor deformation of Augustine volcano to help understand the magma plumbing system driving surface deformation.

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Application of GPR Technology for Detecting Bedrock under Conductive Overburden and Geological Survey (전도성 충적지반의 지질 및 하부 기반암 조사를 위한 지하레이다(GPR)의 적용)

  • 윤운상;배성호;김병철;김학수
    • Tunnel and Underground Space
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    • v.5 no.2
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    • pp.114-122
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    • 1995
  • The principle and applications of GPR(Ground Penetrating Radear) are familiar to engineering geologists and geophsicists as very attractive technique for continuous high resolution images of the subsurface. However, the main limitation of GPR is obviously related to presence of clayey or silty conductive soils, resulting in complete attenuation of radar signals. This difficulty gives hesitation for the exploration of the deeper targets for example detecting bedrock, particularly in Korean situation that most regions have conductive overburden. In order to prove usefulness of geological survey with GPR in that situation, the technique was tried to investigate depth of bedrock under thick conductive overburden and the other geolocgical informations for the constructionof foundation in the Dongbu apartment site, Kimhae. The reflection patterns on the processed GPR sections are well correlated with the geotechnical units-bedrock, alluvium, landfill unit and their internal layer-boundaries of boring data before GPR survey, except upper contact of bedrock. The isopach maps of the geotechnical units for the 3-D interpretations are made from GPR sections. The maps provided useful geological information that bedrock was distributed as plain and valley with 22~27m depth under alluvium unit (this depth is 5~8 m deeper than drill log) and sedimentary layers subsided and bended along growth fault with NNE strike/15$^{\circ}$SE dip in alluvium unit.

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Implementation of portable multifunction digital compass (휴대용 다기능 디지털 컴퍼스 구현)

  • An, Gwang-Hui;Kim, Hong-Seok
    • The Journal of Engineering Research
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    • v.7 no.1
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    • pp.61-70
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    • 2005
  • Conventional geological survey utilizes the manual compass for mass amount of measurements of the geologic structure. Portable multifunction digital compass system was required by more detailed geological survey, due to increasing construction for rock slopes and runnels. In this paper, the system was implemented by using Intel PXA 255 embedded board as a system controller, and was composed of tilting sensor, digital azimuth sensor, and Global Positioning System (GPS) module. After the measured location, strike, and the angle of dip with our implemented system were transmitted to Personal Digital Assistant (PDA) or notebook, these data could be used for geologic structure analysis. It is expected that the availability of cheap and improved digital compass will reduce the coast and time of geological survey extensively.

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The geophysical survey in shallow water and transitional region

  • Ashida Yuzuru
    • 한국지구물리탐사학회:학술대회논문집
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    • 2002.09a
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    • pp.1-15
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    • 2002
  • In the present paper, the marine reflection seismic survey, the survey using Chirp sonar, the detail topographic survey by narrow multi-beam sounding machine, the sea bottom geological condition survey by side-scan sonar, the sea bottom sampling by core sampler and the positioning by DGPS as the geophysical survey in shallow and transitional region are introduced by placing emphasis on hardware configuration.

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Mapping Submarine Bathymetry and Geological Structure Using the Lineament Analysis Method

  • Kwon, O-Il;Baek, Yong;Kim, Jinhwan
    • The Journal of Engineering Geology
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    • v.24 no.4
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    • pp.455-461
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    • 2014
  • The Honam-Jeju, Korea-Japan, and Korea-China subsea tunnel construction projects have drawn significant attention since the early 2000s. These subsea tunnels are much deeper than most existing natural shallow sea tunnels linking coastal areas. Thus, the need for developing new technologies for the site selection and construction of deep subsea tunnels has recently emerged, with the launch of a research project titled "Development of Key Subsea Tunnelling Technology" in 2013. A component of this research, an analysis of deep subsea geological structure, is currently underway. A ground investigation, such as a borehole or geophysical investigation, is generally carried out for tunnel design. However, when investigating a potential site for a deep subsea tunnel, borehole drilling requires equipment at the scale of offshore oil drilling. The huge cost of such an undertaking has raised the urgent need for methods to indirectly assess the local geological structure as much as possible to limit the need for repeated borehole investigations. This study introduces an indirect approach for assessing the geological structure of the seafloor through a submarine bathymetry analysis. The ultimate goal here is to develop an automated approach to the analysis of submarine geological structures, which may prove useful in the selection of future deep subsea tunnel sites.

Shallow subsurface structure of the Vulcano-Lipari volcanic complex, Italy, constrained by helicopter-borne aeromagnetic surveys (고해상도 항공자력탐사를 이용한 Italia Vulcano-Lipari 화산 복합체의 천부 지하 구조)

  • Okuma, Shigeo;Nakatsuka, Tadashi;Komazawa, Masao;Sugihara, Mitsuhiko;Nakano, Shun;Furukawa, Ryuta;Supper, Robert
    • Geophysics and Geophysical Exploration
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    • v.9 no.1
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    • pp.129-138
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    • 2006
  • Helicopter-borne aeromagnetic surveys at two different times separated by three years were conducted to better understand the shallow subsurface structure of the Vulcano and Lipari volcanic complex, Aeolian Islands, southern Italy, and also to monitor the volcanic activity of the area. As there was no meaningful difference between the two magnetic datasets to imply an apparent change of the volcanic activity, the datasets were merged to produce an aeromagnetic map with wider coverage than was given by a single dataset. Apparent magnetisation intensity mapping was applied to terrain-corrected magnetic anomalies, and showed local magnetisation highs in and around Fossa Cone, suggesting heterogeneity of the cone. Magnetic modelling was conducted for three of those magnetisation highs. Each model implied the presence of concealed volcanic products overlain by pyroclastic rocks from the Fossa crater. The model for the Fossa crater area suggests a buried trachytic lava flow on the southern edge of the present crater. The magnetic model at Forgia Vecchia suggests that phreatic cones can be interpreted as resulting from a concealed eruptive centre, with thick latitic lavas that fill up Fossa Caldera. However, the distribution of lavas seems to be limited to a smaller area than was expected from drilling results. This can be explained partly by alteration of the lavas by intense hydrothermal activity, as seen at geothermal areas close to Porto Levante. The magnetic model at the north-eastern Fossa Cone implies that thick lavas accumulated as another eruption centre in the early stage of the activity of Fossa. Recent geoelectric surveys showed high-resistivity zones in the areas of the last two magnetic models.

Analysis of Reservoir Vulnerability Based on Geological Structure Around Pohang Earthquake (포항지진 발생 주변지역 지질특성에 따른 저수지 취약성 해석)

  • Lim, Sung Keun;Song, Sung-Ho;Yu, Jaehyung
    • Journal of the Earthquake Engineering Society of Korea
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    • v.22 no.3
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    • pp.169-174
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    • 2018
  • A total of 594 reservoirs (17%), which are managed by KRC, equipped with earthquake-resistant facilities whereas remaining ones did not. In addition, reservoirs were placed without the effect of geological structures (i.e., fault and lineament). Therefore, development on technique for alleviating the potential hazards by natural disasters along faults and lineaments has required. In addition, an effective reinforcement guideline related to the geological vulnerabilities around reservoirs has required. The final goal of this study is to suggest the effective maintenance for the safety of earth fill dams. A radius 2 km, based on the center of the reservoir in the study area was set as the range of vulnerability impacts of each reservoir. Seismic design, precise safety diagnosis, seismic influence and geological structure were analyzed for the influence range of each reservoir. To classify the vulnerability of geological disasters according to the fault distribution around the reservoir, evaluation index of seismic performance, precise safety diagnosis, seismic influence and geological structure were also developed for each reservoir, which were a component of the vulnerability assessment of geological disasters. As a result, the reservoir with the highest vulnerability to geological disasters in the pilot district was analyzed as Kidong reservoir with an evaluation index of 0.364. Within the radius of 100km from the epicenter of the Pohang earthquake, the number of agricultural infrastructure facilities subject to urgent inspections were 1,180 including reservoirs, pumping stations and intakes. Four reservoirs were directly damaged by earthquake among 724 agricultural reservoirs. As a result of the precise inspection and electrical resistivity survey of the reservoir after the earthquake, it was reported that cracks on the crest of reservoirs were not a cause of concern. However, we are constantly monitoring the safety of agricultural facilities by Pohang aftershocks.

Stratigraphical Study on Tertiary System of Pohang Area Compared with Petrogeologies of Japan (포항(浦項)의 제삼기층(第三紀層)과 일본유전지질(日本油田地質)의 층위대비연구(層位對比硏究))

  • Chang, Seyong
    • Economic and Environmental Geology
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    • v.9 no.1
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    • pp.1-11
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    • 1976
  • It is believed that geological survey, drilling and geophysical survey which was carried out on Tertiary deposits in Pohang is a valuable but through the studying of many Tertiary sediments in Japan discovered many questions on analysis of final report prepared by National geological survey. The main reason is: 1. The seismic sound velocity which have regulated in the final report prepared by geological survey for Tertiary deposits in Pohang was 1,500-2,000m/sec in spite of oil bearing sediments of same age in Japan are 2,000-3,800m/sec. These may means the requirement of reconsideration of seismic velocity for Tertiary deposits in Pohang and required to have a dipper drilling. 2. Stratigraphically, geophysically, and paleontologically, the Tertiary deposits in Pahang land area is similar with that of Nishiyama-Hunakawa formations of Akita oil field in Japan. Nishiyama-Hunakawa formation is the main oil bearing formation in Japan. 3. Those valcanic rock including andestitic rock and liparitic rock which have extensively distributed over either at land area or at sea bottom, assumed by geological survey as the base of Tertiary sediments. But in case of Japan many oil bearing deposits are in over laid by these kind of volcanic rock. Therefore a possible of same condition with Japan is presumable on Tertiary sediments in Pohang. 4. It is believed that the Tertiary sediments of land area in Pohang is the extension of offshore basin but is wandering that the final report submitted by geologic survey have not remain any word on report of ECAFE discribed so much problematics as followed: A. Although it was assumed that no great thickness exceeding 1,000 meters, or major structures would be encountered in the Tertiary offshore sequence, it was hoped that shallow hydrocarbon deposits might be found, because these sediment are lithologically similar to those of the same age in the producing area of the northwest Honshu region of Japan where hydrocarbon are extracted from depths of only 500 to 600 meters. B. Four possible hydrocarbon trap conditions are represented in the survey area: anticlinal folds, faults, pinch outs, along the igneous basement and lateral facies changes. C. Most of the prime possible reservoir area are beyond the 50 meter water depth mark, except for the structures in Yonil Bay. D. Despite the shallowness of the offshore basin, sufficient trap condition exist in the area to warrant further exploration for hydrocarbon. 5. All of the problems mentioned above have gave us a strong reasons to have us hesitating to make a final conclusion on Tertiary problems in Pohang, before to have a drill to a depth to 3,000 meters or more whatever it is the Tertiary or a Mesozoics below 1,000 meters.

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Geophysical Prospecting for Geothermal Resources at Northern Part of Kumseongsan, Euiseong (의성 금성산 북부지역의 지열자원 지구물리탐사)

  • Lee, Gidong;Han, Kihwan;Kim, Kibeom;Lee, Jongmoon
    • Journal of the Korean GEO-environmental Society
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    • v.7 no.6
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    • pp.35-44
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    • 2006
  • Various geophysical methods and geological survey were applied for prospecting of geothermal resources and the attitude of volcanic body at northern part of Kumseongsan, Euiseong. They include magnetic, self-potential, radioactive and resistivity methods, temperature logging near the earth's surface and geological survey. The results of this study are summarized as follows. Various geophysical anomalies is related to the geologically Cretaceous conduit. Anomalies of resistivity and temperature logging seem to be related to the geological structure and terrestrial heat. Small radioactive and self-potential anomalies seem to be associated with chemical character of rocks. The sedimentary rocks dip steeply toward the volcanic rocks, aquifuge. Ideal geological structure for bearing ground water and geothermal resources was founded in the study area. The study area and the adjacent two hot springs area consist of Cretaceous sedimentary and volcanic rocks, and have similar geology.

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