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タイトル: Generation and Propagation of G Waves from the Niigata Earthquake of June 16, 1964 : Part 1. A statistical analysis.
その他のタイトル: 1964年6月16日新潟地震によるG波の発生と伝播 : (1)統計的研究
著者: Aki, Keiiti
著者(別言語): 安芸 , 敬一
発行日: 1966年7月25日
出版者: 東京大学地震研究所
掲載誌情報: 東京大学地震研究所彙報. 第44冊第1号, 1966.7.25, pp. 23-72
抄録: The G waves from the Niigata earthquake of June 16, 1964 recorded at the world-wide standard seismograph stations are studied for the purpose of elucidating the source mechanism. The observed radiation pattern of G2 waves with period 200sec indicates a source of pure thrust fault with the strike direction N20°E. This result is in excellent agreement with those from the first motion study as well as from the field studies of the epicentral area by various geological and geophysical methods. The amplitude and phase spectra for shorter periods are variable, and a statistical approach is taken in their investigation. Both G2 and G3 waves with periods shorter than about 150sec show a statistical behavior expected for a finite sample of a smoothed Gaussian noise. The factors causing this randomization may be 1) the source complex, 2) the interference due to lateral refraction, and 3) the interference with higher modes or body waves. The near-pole phenomena are demonstrated on a before-after picture by the forward extrapolation of G2 wave fronts and the backward extrapolation of G3 wave fronts. It is confirmed that the π/2 polar phase advance is a good first approximation. However, the "after" picture obtained from G3 waves shows much greater irregularity than the "before" picture obtained from G2 waves, and it is difficult to find the source mechanism by the phase equalization of G3 waves. The apparent Q values estimated from averaged spectra vary from 100 to 200 for the periods from 200 to 50sec.
新潟地震によるG波の世界標準地震計の記録を用いて,発震機構をしらべた.周期200秒のG2波の振幅位相スペクトルの分布は, N20°Eの走行をもつ逆断層で説明できる.この結果はP波初動の分布や,各種方法による震源地調査の結果とよく一致する.
URI: http://hdl.handle.net/2261/12237
ISSN: 00408972


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