著者

笹谷 努

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.26, no.1, pp.67-76, 1973

被引用文献数

1

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A particular type of phase designated as the P₂-phase is found in the P wave train around 9 seconds after the first arrival of the earthquake off east coast of Aomori prefecture of March 29, 1965. In the previous paper, the P₂-phase has been interpreted as the stopping phase from the analysis of the motion direction of this phase. In the present paper, the P₂-phase is re-examined in the wave form of the theoretical displacement of P wave from a fault near the earth's surface, because the unreasonable interpretation for the fault length and the rupture velocity has been given. The examination shows that the P₂-phase concerned does not consist of the stopping phase, but of reflected sP phase, and that the wave form of direct P wave from a fault with a fault length greater than its depth may be disturbed by the reflected waves.<br>The seismic moment and the apparent stress for the present earthquake are estimated to be 3.20&times;10²⁵dyne-cm and 5 bars, respectively.