関東平野の深部基盤構造と長周期地震動リスク

DOI Web Site Web Site 被引用文献5件 参考文献11件
  • 古村 孝志
    東京大学大学院情報学環総合防災情報研究センター 東京大学地震研究所

書誌事項

タイトル別名
  • Risk of Long-period Ground Motion due to the Deep Basement Structure of the Kanto Basin
  • Radiation and Generation of Short- and Long-Period Ground Motions from the 2011 Off Tohoku, Japan, Mw9.0 Earthquake
  • カントウ ヘイヤ ノ シンブ キバン コウゾウ ト チョウ シュウキ ジシンドウ リスク
公開日
2014
DOI
  • 10.5026/jgeography.123.434
公開者
公益社団法人 東京地学協会

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説明

In the Kanto basin, long-period (T = 6-8s) ground motions develop during large (M > 7) earthquakes due to the resonance of surface waves with thick (> 3000m) sedimentary layers covering rigid bedrock. Such long-period ground motions can cause significant damage to modern large-scale, long natural-period structures such as skyscrapers, oil storage tanks, and long bridges. Therefore, it is important that residents of modern Tokyo metropolitan area cities be forewarned about the potential for such disasters. In the present paper, the development of large and long-duration, long-period ground motions in central Tokyo is investigated by analyzing waveform data from recent large earthquakes obtained from dense seismic networks extending over the Kanto basin. It is demonstrated that the interaction of surface waves with the three-dimensional sedimentary structure beneath the Kanto region causes peculiar and directional dependencies related to the amplification strength of the long-period ground motions. For example, the long-period ground motions resulting from earthquakes occurring in northern Japan cannot develop efficiently in central Tokyo. This might be one reason for the relatively weak long-period ground motions observed in central Tokyo during the 2011 Off Tohoku M 9.0 earthquake compared to those of other M 7-8 class events, such as the 1944 Tonankai (M 7.9) and the 2003 Off Tokachi (M 8.0) earthquakes. The results of computer simulations using detailed subsurface structures and source-slip models for an anticipated Nankai Trough M 8.7 earthquake indicates that the strength of long-period ground motions in central Tokyo can be expected to be at least double than those observed during the 2011 Off Tohoku earthquake.

収録刊行物

  • 地学雑誌

    地学雑誌 123 (4), 434-450, 2014

    公益社団法人 東京地学協会

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