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Investigation of shallow to deep subsoil structures in urban area by means of microtremors and its application to an assessment for regional seismic input motions.

Research Project

Project/Area Number 02452207
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field Building structures/materials
Research InstitutionHokkaido University

Principal Investigator

KAGAMI Hiroshi  Hokkaido Univ., Fac. of Eng., Professor., 工学部, 教授 (70016476)

Co-Investigator(Kenkyū-buntansha) MURAKAMI Hitomi  Hokkaido Univ., Fac. of Eng., Research Associate, 工学部, 助手 (10201807)
OKADA Shigeyuki  Hokkaido Univ., Fac. of Eng., Associate professor, 工学部, 助教授 (50125291)
Project Period (FY) 1990 – 1991
Project Status Completed (Fiscal Year 1991)
Budget Amount *help
¥5,700,000 (Direct Cost: ¥5,700,000)
Fiscal Year 1991: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1990: ¥4,300,000 (Direct Cost: ¥4,300,000)
KeywordsMicrotremors / Seismic baserock / Ishikari Plain / Spectral analysis / Site effect / Tree dimensional model
Research Abstract

The purpose of this study is to develop a feasible method for evaluating seismic input motions in an urban area by means of experimental way and Sapporo urban area, northern Japan, was selected as a test field.
Microtremors measurement was adapted for this study because of its easy applicability for detecting subsoil conditions. At the first, the observation system was upgrading in both terms of hardware and software. An A/D converter was installed in a laptop computer and a real time monitoring was introduced by computer program. With this system daytime measurements in busy business district can be performed in spite of low S/N ratio.
Extensive measurements of long-period microtremors were conducted in Sapporo urban area in 1990 and 1991. Seven observation lines parallel to the coastal line and two lines perpendicular to these were set up, covering the area of about 40 x 40 kilometers, obtaining records at totally 183 sites. One reference site was set up at Hokkaido University to monitor the time variation of microtremors during the period of measurements.
Spectral ratios were obtained for each site by dividing the Fourier spectra by the corresponding spectra at the reference site. These ratios were plotted on a map for each period of 0.5, 1, 2 and 4 second and four contour maps were drawn as seismic microzonig maps. These maps were verified by various of small number of deep drilling data, three strong motion records and seismic intensity distribution data of the 1982 Off-Urakawa earthquake.

Report

(3 results)
  • 1991 Annual Research Report   Final Research Report Summary
  • 1990 Annual Research Report
  • Research Products

    (9 results)

All Other

All Publications (9 results)

  • [Publications] Okada,S.: "Two Dimensional Analysis on Site Effects in Sapporo Urban Region,Japan,Based on Observation of 1to5 second Microtremors." Proceedings of Forth international Conference on Seismic Zonation. 2. 377-384 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kagami,H.: "Assessment of Site Effects on Seismic Input Motions in the Sapporo Urban Region,Northern Japan Utilizing Long Period Microtremors." Proceedings of the loth World Conference on Earthquake Engineering. (1992)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Shigeyuki Okada, Hitomi O. Murakami and Hiroshi Kagami: "Two Dimensional Analysis on Site Effects in the Sapporo Urban Region, Japan, Based on Observation of 1 to 5 Second Microtremors" Proceedings of Forth International Conferenceon Sismic Zonation. 2. 377-384 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Hiroshi Kagami, Shigeyuki Okada, Hitomi O. Murakami and Shinobu Sakai (1992).: "Assessment of Site Effects on Seismic Input Motions in the Sapporo Urban Region, Northern Japan Utilizing Long Period Microtremors" Proceedings of the 10th World Conference on Earthquake Engineering. (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Okada,S.: "Two Dimensional Analysis on Site Effects in Sapporo Urban Region,Japan,Based on observation of 1 to 5 second Microtremors." Proceedings of Forth International Conference on Seismic Zonation. 2. 377-384 (1991)

    • Related Report
      1991 Annual Research Report
  • [Publications] Kagami,H.: "Assessment of Site Effects on Seismic Input Motions in the Sapporo Urban Region,Northern Japan Utilizing Long Period Microtremors." Proceedings of the 10th world conference on Earthquake Engineering. (1992)

    • Related Report
      1991 Annual Research Report
  • [Publications] 岡田 成幸: "やや長周期微動観測を利用した石狩平野の地盤震動性状の把握" 日本建築学会北海道支部研究報告集. 64. 67-70 (1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] 鏡味 洋史: "やや長周期の微動観測と地震工学への適用 (18)石狩平野における微動振幅と深部地下構造との対応(2)" 地震学会講演予稿集. (1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] S.Okada: "Two Dimensional Analysis on Site Effects in the Sapporo Urban Region,Japan,Based on Observation of 1 to 10 Second Microtremors" International Conference on Seismic Zonation. 4. (1991)

    • Related Report
      1990 Annual Research Report

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Published: 1990-04-01   Modified: 2016-04-21  

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