著者
阿部 邦昭 岡田 正実
出版者
公益社団法人 日本地震学会
雑誌
地震 第2輯 (ISSN:00371114)
巻号頁・発行日
vol.46, no.1, pp.25-34, 1993-06-24 (Released:2010-03-11)
参考文献数
9
被引用文献数
1 1

We succeeded in explaining a small tsunami on a vertical displacement field of a pure strike-slip fault. The Izu-Oshima Kinkai Earthquake (M=6.5) of February 20, 1990, being accompanied with a small tsunami, was modeled as a pure strike-slip fault on a focal mechanism solution and aftershock area. The sinistral strike slip fault with a plane of 15×12km2, dip of almost 90° and strike of N0°E was assumed at the epicenter.A numerical experiment on the vertical displacement field reproduced the observed tsunami fairly well. The computation was carried out on a linear framework using a mesh of 1km, time step of 1 sec and an additional fine mesh of 0.25km in the vicinity of tide stations. The assumed dislocation of 1m explained the observed amplitude at the nearest tide station. Comparison of waveforms between model and four observations supports the model.Furthermore, a spectral analysis was attempted to reveal predominant frequencies of the observed tsunami. The observed predominant frequencies were explained from wave lengthes characteristic to the pure stlike-slip fault. A strong azimuth dependence is one of the characteristic properties of the pure strike slip tsunami. An unexplainable predominant frequency was attributed to the reflected wave from the Izu Oshima Island.

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外部データベース (DOI)

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@volcano_tan @L0k1_p0y0 3ページ目に純粋横ずれ断層でも上下変位が表れ、隆起と沈降が対で断層の端に表れ、極性は両端で互いに反対になるとの記述があります。参考にして頂ければ幸いです。https://t.co/6e9a54rX62
1990年2月20日の伊豆大島近海の地震Mw6.4は、横ずれ型だが津波が発生(大島町と南伊豆町で最大30cm)した。純粋横ずれでも、ずれの端で行き場を失った部分が隆起し、反対側はそれをうめる形で沈降して、海底に上下変位が生じる。 「横ずれ断層地震による津波の励起」 https://t.co/dugnu3EVAy

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