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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Geophysics and Geophysical Exploration
Journal Basic Information
Journal DOI :
Korean Society of Earth and Exploration Geophysicists
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Volume & Issues
Volume 8, Issue 4 - Nov 2005
Volume 8, Issue 3 - Aug 2005
Volume 8, Issue 2 - May 2005
Volume 8, Issue 1 - Feb 2005
Selecting the target year
Ground Motion Evaluation from the Fukuoka Earthquake
Park, Dong-Hee ; Yun, Kwan-Hee ; Chang, Chun-Joong ; Choi, Weon-Hack ; Lee, Dae-Soo ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 109~119
The ground-motion (GM) attenuation relations available in Korea has required the validation process for large earthquakes since most of them were developed based on small earthquake database. The Fukuoka earthquake (M=7.0) that occurred near the Korean Peninsula provides invaluable data to indirectly evaluate the attenuation characteristics of the strong GM in Korea. The GM levels (PGA, SA) obtained from the KIK-net downhole stations near the epicenter (R<100km) are reasonably predicted by the GM attenuation relation developed by KEPRI in 2003 for the Kori NPP site, the result of which validates the use of KEPRI GM attenuation relation for predicting GM induced by future large earthquakes. Also, the comparison between the Osaki spectra and response spectra of KIK-net downhole data reveals that the amplitude levels of Osaki spectra are higher than the spectra from KIK-net stations which are believed to be installed at the seismic basement.
Approach to the Earthquake Prediction by Analyzing Foreshocks ofLarge Korean Historical Earthquakes
Lee, Sang-Hyeon ; Lee, Kie-Hwa ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 115~121
Seismicity changes associated with foreshocks of large Korean historical earthquakes of MMI > VIII are investigated for earthquake prediction study. A number of tests showed that b-values of foreshocks associated with these large earthquakes are most stable for precursor period of 13 years before the earthquake and rectangular source area of 1.1' by 1.1' around the epicenter. The b-values of foreshocks for 11 large events of MMI > VIII for the above foreshock area and precursor period turns out to be smaller than the value of 0.36 for the whole historical earthquakes with average 0.27. Epicenters of these foreshocks of small b-values are distributed close to the location of the main large earthquake. These observations indicate a possibility of predicting large earthquakes by closely monitoring the change of b-value for an extended period over decades in the Korean peninsula.
Failure Zone Estimation from the correlation between the Temperature in Slope and the Soil Nail Strain
Chang, ki-Tae ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 123~130
It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure zone resulted from weathering effect and other factors. The FBG sensor system is used to estimate the correlations between the temperature and the slope in Kimhae, and to find a failure zone in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the correlation. For instance, the zone of high temperature fluctuation can be regarded as one of the possible sliding zone due to the weathering effect while the constant temperature depth of the ground, if exists would not be relatively affected by the weathering process.
Geological Structure and Depositional Environments in the Dok Island, East Sea
Huh, Sik ; Park, Cha-Hong ; Yu, Hai-Soo ; Han, Sang-Joon ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 131~135
A maximum of 3 km thickness of sediments were deposited above basement deformed by volcanic activities around the Dok Island. As the geological structure, the tension caused the basement-involved normal faults in the early stage of basin formation, whereas the sediment layers showed normal faults, volcanic domes and sills caused by volcanic activities. From the distribution of volcanics in order of age at the Ulleung Basin, volcanic activities were increased toward the northeastern direction(toward Dok Island). The study area is characterized by extensional crustal deformation before sediment deposition during the Early or Middle Miocene age. After the Late Miocene age, the basin was deformed by deep buried volcanics or subsidence of basin, in consequence, became complex geological structures.
Tension Wire Sensor of shallow failure detection for the real time slop stabilization
Chang, Ki-Tae ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 137~143
Early detection of premonitory symptom of slope movement ensures tremendous saving of lives and repair costs from catastrophic disaster. Therefore, it is essential to constantly monitor the performance and integrity of both reinforced and un-reinforced cut slopes. We developed a novel monitoring system by using tension wire sensors. It's advantages are highly sensitivity, simple installation, large displacement measurement, durability of system, capability of remote sensing. Real-time measurement of slope surface movement is shown graphically and it gives a warning when the monitored value exceeds a given threshold level so that any sign of abnormal slope movement can be easily perceived.
Relation of Groundwater Quality to Land Use on Ulsan Urban area
Im, Hyun-Chul ; , ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 145~152
216 groundwater samples for inorganic constituents and 168 samples for VOCs in the Ulsan urban ares and analyzed to relate groundwater chemistry to four land use zones, residence․commercial, industrial, agricultural, and forestry. In general, Na and Cl concentrations in groundwater were high in residence․commercial zone near Taehwa river due to residual saline. Although
contents is high in agricultural zone and VOCs content is high in industrial zone, it seems difficult to relate groundwater pollution to land use zone. Even though groundwater pollution of the area is still low, continuous monitoring is necessary because the city is expanding.
Efficient Triangulation Algorithm for Constructing the Model Surfacefrom the Interpolation of Irregularly-Spaced Laser Scanned Data
Shon, Howoong ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 153~157
A discussion of a method has been used with success in terrain modelling to estimate the height at any point on the land surface from irregularly distributed samples. The special requirements of terrain modelling are discussed as well as a detailed description of the algorithm and an example of its application.
Surface Flux Measurements at King Sejong Station in West Antarctica: Ⅱ. Turbulent exchanges of sensible heat and latent heat in the austral summer of 2002-2003
Choi, Tae-Jin ; Lee, Bang-Yong ; Lee, Hee-Choon ; Kim, Seong-Joong ; Hong, Sung-Min ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 159~167
Turbulent fluxes of sensible heat and latent heat were analyzed at King Sejong station in the austral summer of 2002 (December) and 2003 (January and February). Monthly mean air temperatures of January and February (2.2
C) were similar to those averaged over 1988 to 2001. Precipitation was less in January and greater in February than those averaged over last 14 years. In December of 2002 and January, there was precipitation primarily when easterly wind blew usually. The frequency of snowfall was equal to or larger than that of rainfall. In the mean while, precipitation primarily in forms of rainfall occurred with westerly wind in February. In addition, while for easterly wind, temperature and humidity was low, temperature and humidity were high in case of westerly wind. Based on flux footprint, measured flux mainly came from within 300 m with maximum of 40 m upwind, indicating the insignificant role of the sea around the study site. Half-hourly downward short wave radiation amounted up to ∼ 1000
and net radiation ranged from -50 to 600
. Half-hourly sensible heat flux was positive at daytime with maximum of ∼ 400
, except the 27th and 28th in February of 2003 when it was negative all day despite of positive net radiation at short daytime. Latent heat flux was positive with maximum of ∼ 130
. Depending on wind direction, the partitioning of net radiation into the sum of sensible heat flux and latent heat flux was larger than 0.8, indicating the strong source of the land surface for the atmospheric heating. The daytime averaged Bowen ratio (=sensible heat flux /latent heat flux) was significantly greater than 1, indicating that sensible heat flux was the main source to heat the atmosphere over the site.
Late Quaternary Seismic Stratigraphy and Sedimentation of the Southeastern Continental Shelf, Korea Strait
Yoo Dong-Geun ; Lee Chi-Won ; Min Gun-Hong ; Lee Ho-Young ; Choi Joung-Gyu ; Park Soo-Chul ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 201~206
Interpretation of high-resolution seismic profiles from the southeastern continental shelf of Korea reveals that the sedimentary deposits consist of seven seismic units formed during the late Quaternary. These units comprise lowstand, transgressive, and highstand systems tracts. The lowstand systems tract consists of a lowstand prograding wedge (SU1) and a mass flow deposit (SU2) including slumps and slides. The transgressive systems tract contains four seismic units: an ancient beach/shoreface deposit (SU3), a channel-fill deposit (SU4), a transgressive sand layer (SU5), and a transgressive sand ridge (SU6). The highstand systems tract consists of an inner-shelf mud deposit (SU7) derived from the Nakdong and Seomjin rivers during the last 6 ka when sea level was close to the present level.
3-D EM Modeling Using Approximate Integral Equation Method for the Models with Non 1-D Background Conductivity
Lee Seong Kon ; Zhdanov Michael S. ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 207~217
We present a new approximate formulation of the integral equation (IE) method for models with variable background conductivity. This method overcomes the standard limitation of the conventional If method related to the use of a horizontally layered background only. The new approximate IE method still employs the Green's functions for a horizontally layered 1-D model. However, the new method allows us to use an inhomogeneous background with the IE method. The method was carefully tested for modeling the EM field for complex structures with a known variable background conductivity. It can find wide application in modeling EM data for multiple geological models with some common geoelectrical features, like a known inhomogeneous overburden, or salt dome structures.
Laboratory Study on the Electrical Resistivity Characteristics with Contents of Clay Minerals
Park Mi-Kyung ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 218~223
This study considers to electrical resistivity characteristics for clay minerals types and contents in fractured and fault zone. The electrical resistivity is measured for an artificial agar specimen with clay minerals instead of a natural rock. The artificial agar specimen with clay minerals was special worked in study. The clay minerals used are Kaolinite and Montmorillonite in test, the clay mineral contents increases until
to the same specimen. As results, the electrical resistivity of the specimen decreased gradually as the clay mineral contents increases for all types of clay minerals. Montmorillonite shows remarkably lower resistivity than Kaolinite, although its clay content is fewer than that of Kaolinite. Also, a proposed experimental expression shows a good correlation coefficient as high as 0.89 or more in all clay minerals.
Multi-purpose Geophysical Measurements System Using PXI
Choi Seong-Jun ; Kim Jung-Ho ; Sung Nak-Hun ; Jeong Ji-Min ;
Geophysics and Geophysical Exploration, volume 8, issue 3, 2005, Pages 224~231
In geophysical field surveys, commercial equipments often fail to resolve the subsurface target or even sometimes fail to be applied because they do not fit to the various field situations or the physical properties of the medium or target. We developed a geophysical measurement system, which can be easily adapted for the various field situations and targets. The system based on PXI with A/D converter and some stand alone equipment such as Network Analyzer was applied to borehole radar survey, borehole sonic measurement and electromagnetic noise measurement. The system for borehole radar survey consists of PXI, Network Analyzer, dipole antennas, GPIB interface is used for PXI to control Network Analyzer. The system for borehole sonic measurement consists of PXI, 24 Bit A/D converter, high voltage pulse generator, transmitting and receiving piezoelectric sensors. The electromagnetic noise measurement system consists of PXI, 24 Bit A/D converter, 2 horizontal component electric field sensors and 2 horizontal and 1 vertical component magnetic filed sensors. The borehole radar system has been successfully applied to detect the width of the artificial tunnel through which the borehole pass and to image buried steel pipe, while the commercial borehole radar equipment failed. The borehole sonic system was tested to detect the width of artificial tunnel and showed a reasonable result. The characteristic of electromagnetic noise was grasped at an urban area with the data from the electromagnetic noise measurement system. The system is also applied to characterize the signal distortion by induction between the electric cables in resistivity survey. The system can be applied various geophysical problems with a simple modification of the system and sensors.