15. Study on Distant Tsunamis along the Coast of Japan : Part 2, Tsunamis of South American Origin

概要

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Making use of data of tsunamis which occurred in the region of South America, frequencies of tsunami generation and of tsunami which propagated to Japan are investigated. Refraction diagrams and the distributions of tsunami height for seven tsunamis which propagated across the Pacific Ocean are shown. Especially, these phenomena along the coast of Japan are shown in detail with the aid of mareograms. The spectral analysis of records obtained in Japan is made for five tsunamis. The generating area of the Chilean tsunami of 1960 is estimated by means of an inverse refraction diagram. This source includes the area of aftershock activity extending about 800 km in an elongated shape.|南米太平洋沿岸で発生した歴史津波の資料によると,波源付近の波高が10m程度の津波によつて日本,ハワイは数回相当な被害を受けている.1900年以後は我が国においても検潮儀によつて7個の津波が観測された.このうち1960年11月20日のペル沖で起きた地震(M=6.75)によつて,微小な津波を観測した例もある.マグニチュードが8.3以上の地震に伴なう津波は,例外なく全太平洋沿岸地域で観観されているが,8.0以下の地震による過去の津波は,日本沿岸で波高50cm以下の微弱なものである.
1968-06-20