• Title/Summary/Keyword: Japan Earthquake

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A investigation on the responses of conductive structures of Korean Peninsula using EM modeling

  • Yang, Jun-Mo;Oh, Seok-Hoon;Lee, Duk-Kee;Kwon, Byung-Doo;Youn, Yong-Hoon
    • 한국지구과학회:학술대회논문집
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    • 2004.02a
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    • pp.52-57
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    • 2004
  • Korean Peninsula located between Japan and China where earthquakes frequently occur, have little geophysical observation despite its tectonic importance. This study suggests the inland conductive structures inferred from GDS data measured in Korean Peninsula and try to interpret induction arrows quantitatively with the aid of 2- and 3-D geomagnetic induction modeling. Ogcheon Belt (OCB) and Imjin River Belt (IRB) are regarded as main conductive structures in Korea Peninsula, the induction arrows for the period of 60 minutes show very weak anomaly due to sea effect, which is supported by the results of 3-modeling also. However, for the period of 10 minutes, induction arrows at YIN and ICHN show anomalous patterns considered as the effect of IRB in spite of sea effect. The results of 2-D modeling which simplify geological situations provide overall information on IRB

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Recent Earthquake Activity in and around Kyeongsang Basin (최근의 경상분지 일원에서의 지진활동)

  • 전정수
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1998.10a
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    • pp.391-398
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    • 1998
  • To understand the current seismic activity and regional tectonic status in and around Gyeongsang basin, Korea Institute of Geology, Mining, and Materials(KIGAM) has performed the earthquake monitoring around the Gyeongsang basin since early 1980's with portable analog seismic instruments for about two months every year. As a part of POSEIDON project, Korea-Japan joint observation around gyeongsang basin in 1991 and 1992, was performed using by temporary seismic station. KIGAM has been continuously operated nine short-period 3-components digital seismic stations since the end of 1994. During the observation period, 247 earthquakes were analyzed and their magnitude was less than 4.5. In general, we could not find any relationship between seismic activity and known surface geological features. But the epicenters were rather concentrated with NW-SE direction. The most active seismicity was found in Gyeongbuk Gyeongjugun Seokeupri and Hyodongri, and Yeongilgun Janggiri and Guryongpo in land, and in three region along the east coast which are 10km and 30km east off from Gampo and 30km east off from Jongja in offshore.

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Validation of Practical Applicability of Pseudo-resonance Method for Seismic Design of Substation Equipment (변전설비 내진설계를 위한 유사공진법의 적용성 검증)

  • 조양희;조성국;박형기;권경일
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2003.09a
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    • pp.49-57
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    • 2003
  • Lately, a guideline for seismic design of electric substation facilities has been newly prepared and issued. The guideline adopts a new simplified dynamic analysis technique called "pseudo-resonance method" from the design code of Japan. The method can effectively consider resonance effect of structural system during earthquake motion. However, reliability and practical applicability of the method have not been fully guaranteed under the different seismic and engineering situations in Korea. This paper presents a validation study of the pseudo-resonance method for practical seismic analysis. For this purpose, various parametric studies have been performed using recorded earthquake motions and idealized substation equipment models. The results showed that the pseudo-resonance method can be effectively used for the practical seismic design of substation facilities in Korea.

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NUMERICAL SIMULATION OF 1993 TSUNAMI FLOODING ONTO AONAE DISTRICT, OKUSHIRI ISLAND

  • Yamashita, Takao
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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    • 1996.10a
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    • pp.3-6
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    • 1996
  • On July 12, 1993, a large earthquake (M=7.8) occurred off the south-west of Hokkaido, Japan. The tsunami generated by this earthquake caused a disaster which took a heavy toll of lives, more than 200 persons dead, by the flooding of tsunami in the area of Aonae district in Okushiri island. Investigation after the disaster made clear that southern lowland was flooded by the tsunami coming from west about 5 min after the shock and the second tsunami from the east attacked eastern lowland of the Aonae District about 10 min after the shock. (omitted)

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Seismic Response Analysis at Multi-Layered Ground (다층지반의 지진응답해석)

  • Kim, Yong-Seong;Lee, Dal-Won
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2002.10a
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    • pp.329-332
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    • 2002
  • In the present study, in order to apply a cyclic viscoelastic-viscoplastic constitutive model to multi-layered ground conditions during large earthquake, the numerical simulations of the 1995 Hyogoken Nanbu Earthquake at Port Island, Kobe, Japan, were performed by the seismic respons analysis. From the seismic response analysis, it was verified that a cyclic viscoelastic-viscoplastic constitutive model can give a good description of the damping characteristics of clay accurately during large event which induces plastic deformation in large strain range.

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Ground strain estimation for lifeline earthquake engineering

  • Koike, Takeshi;Maruyama, Osamu;Garciano, Lessandro Estelito
    • Structural Engineering and Mechanics
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    • v.25 no.3
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    • pp.291-310
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    • 2007
  • Current seismic design guidelines in Japan are diverse in the seismic ground strain estimates, because the concepts on a horizontally propagating wave model are not consistent in various seismic design guidelines including gas, water and other underground structures. The purpose of this study is (a) to derive the analytical methods to estimate the ground strains for incident seismic waves, (b) to develop a statistical estimation technique of the ground strains, and finally (c) to compare the theoretical estimation with the observed data which was measured at 441 sites in the 1999 Chi-Chi Earthquake in Taiwan.

Estimation of Natural Period by Microtremor Measurement in Shearwall Apartments. (상시미동 측정을 통한 벽식아파트 건물의 고유주기)

  • 강호근
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1999.10a
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    • pp.375-382
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    • 1999
  • The fundamental vibration period of a shearwall apartments cannot estimate accurately by means of empirical formulas specified in present codes, The objective of this paper is to estimate the period of a shearwall apartments by microtremor measurement. A micretremor is the continuous small oscillation of the ground cause by traffic and operation machinery. Microtremors are extensively studied primarily in Japan to estimate conveniently subsurface structures of soil deposits and building vibrations. It is obtained the results that the fundamental periods estimated by microtremor measurement are shorter than those values by dynamic analysis of building.

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