「エッジ効果」に着目した単純な二次元盆地構造の三次元波動場解析

• 川瀬 博

  清水建設和泉研究室

• 松島 信一

  清水建設和泉研究室

• GRAVES Robert W.

  Woodward-Clyde

• SOMERVILLE Paul G.

  Woodward-Clyde

書誌事項

タイトル別名

• Three-dimensional Wave Propagation Analysis of Simple Two-dimensional Basin Structures with Special Reference to “the Basin-Edge Effect”
• 「エッジ効果」に着目した単純な二次元盆地構造の三次元波動場解析--兵庫県南部地震の際の震災帯の成因
• エッジ コウカ ニ チャクモクシタ タンジュン ナ 2ジゲン ボンチ コウゾウ
• Three-dimensional Wave Propagation Analysis of Simple Two-dimensional Basin Structures with Special Reference to “the Basin-Edge Effect”
• 兵庫県南部地震の際の震災帯の成因
• The Cause of the Damage Belt during the Hyogo-ken Nanbu Earthquake

抄録

During the Hyogo-ken Nanbu earthquake of 1995 we have observed conspicuous concentration of damage in an extended area from Suma in the west end of Kobe to the center of Nishinomiya as a form of the so-called damage belt whose width was very small (≅1km) compared to its length (≅20km). We need to find what caused this damage pattern in Kobe. In our previous study we attributed it to “the basin-edge effect”, the amplification effect caused by the constructive interference of the direct S-wave with the basin-induced diffracted/surface waves. However, several researchers have recently reported that seismic motions at the bedrock have a narrow-band distribution due to the directivity effect and that the enhancement of this distribution should be taking place through the interaction of the directivity with the basin structure.<br>In this paper we analyzed again a simple two-dimensional basin model subject to various types of three-dimensional incident waves to confirm that the basin-edge effect is present irrespective of the input wave field. After proving it then we analyzed a simpler basin to fully understand the wave interference phenomena around the edge. It is found that the interference is actually happening twice, first with the basin-induced diffracted P-wave and second with the basin-induced diffracted S-wave plus Rayleigh wave. Quantitative estimation on the contribution of the edge-induced waves during the Hyogo-ken Nanbu earthquake revealed that it must give at least 50cm/s additional amplitude in terms of the peak ground velocity inside the damage belt.

収録刊行物

• 地震　第２輯

  地震　第２輯 50 (4), 431-449, 1998

  公益社団法人 日本地震学会

キーワード

• Sedimentary basin
• Strong motion
• Damage distribution
• Site response
• Directivity
• Hyogo-ken Nanbu earthquake of 1995

詳細情報

• CRID: 1390001204307289216
• NII論文ID: 10002501594
• NII論文ID: 10003848838
• NII書誌ID: AN00305741
• DOI: 10.4294/zisin1948.50.4_431
• ISSN: 18839029
• ISSN: 2186599X
• ISSN: 00371114
• NDL書誌ID: 4435008
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I4435008
• Web Site: https://www.jstage.jst.go.jp/article/zisin1948/50/4/50_4_431/_pdf
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