1993年北海道南西沖地震津波の規模および波源域

DOI Web Site Web Site 被引用文献5件 参考文献10件

書誌事項

タイトル別名
  • Tsunami Magnitude and Source Area of the Southwest off Hokkaido Earthquake in 1993
  • 1993ネン ホッカイドウ ナンセイオキ ジシン ツナミ ノ キボ オヨビ ハ
公開日
1994
DOI
  • 10.4294/zisin1948.47.1_1
公開者
公益社団法人 日本地震学会

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説明

A tsunami was generated off the coast of Oshima Peninsula, the Japan Sea, at 22: 17 (JST) on July 12, 1993. The tsunami killed 231 persons and strongly hit Okushiri Is. located in the source region. A short-period waves of about 7min were predominant around the source area. According to JMA, the epicenter of the main shock was located at 42°47′N, 139°12′E, with a depth of 34km and earthquake magnitude of M=7.8. Based on tide-gauge records, the source area, tsunami magnitude and propagation of the present tsunami are investigated.<br>The source area estimated by means of an inverse refraction diagram is 150×70km2, extending N-S direction on the bathymetric line of 3, 000m. The tsunami source covers the aftershock area. The initial motion of the tsunami began with a down-direction at the tidal stations of Esashi and Iwanai, and the other stations were in an upward direction. It suggests that the sea-bottom on the east side of the tsunami source subsided and that on the west side laying the aftershock area uplifted. Judging from the attenuation of tsunami height with distance, the tsunami magnitude is m=3 on the Imamura-Iida scale. This value is one-grade (tsunami height: 2 times) high comparing with that of tsunamis of the same earthquake magnitude on the Pacific side.<br>The size of source area and the tsunami magnitude were comparable to those of the 1983 Nihonkai-Chubu tsunami. The tsunami also hit the tip of Noto Peninsula, Oki Is. and the east coast of Korea (37°-38°N). The present earthquake was occurred in the gap between the 1940 Shakotan-Oki earthquake and the 1983 Nihonkai-Chubu one, and the southern part of the source area overlapped with the source of the 1741 Kanpo Oshima-Oki tsunami (m=3.5). In the future, there is a possibility of fault motion extending toward the south direction.

収録刊行物

  • 地震　第２輯

    地震　第２輯 47 (1), 1-9, 1994

    公益社団法人 日本地震学会

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