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タイトル: 7. Free Oscillations of the Earth Excited by the Kurile Islands Earthquake 1963
その他のタイトル: 7.1963年エトロフ沖地震による地球自由振動
著者: Abe, Katsuyuki
Sato, Yasuo
Frez, Jose
著者(別言語): 阿部, 勝征
佐藤, 泰夫
発行日: 1970年6月10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48冊第2号, 1970.6.10, pp. 87-114
抄録: Power spectrum data are obtained from the free oscillations of the earth excited by the Kurile Islands earthquake of October 13, 1963, and recorded at eleven stations of WWSSN. Eigen periods of fundamental free oscillations are determined for spheroidal modes 7 to 50, and torsional modes 7 to 46. Equivalent phase velocities are also calculated from the observed periods over the period range from 820 to 170 sec. Observed periods differ slightly from one station to another, and such divergence becomes significant for periods shorter than 350 sec. This difference in the observed period may suggest that the relative amplitudes of the individual modes are affected by a lateral heterogeneity of the upper mantle not deeper than several hundred kilometers. From the amplitude decay with time, the attenuation of free oscillations is estimated for a number of spectral peaks. For the spheroidal oscillation, the average Q factor is 251 for w=13-17 (T=380-480sec), and 200 for n=18-42 (T=200-380sec). Various studies are made on the spectral amplitudes to obtain the source-space function of the earthquake and the pattern of free oscillation modes on the sphere. The results are almost consistent with the earthquake mechanism and mode excitation as revealed by other studies, though the pattern of oscillation is hard to recognize.|世界標準地震観測所のうち11ケ所のプレス.ユーイング長周期地震計の記録をもちい,1963年10月のエトロフ沖地震の地球自由振動を解析した.自由振動の固有周期及び進行波としての位相速度,振幅の大きさ及び位相の分布に関して次の結果が得られた.
URI: http://hdl.handle.net/2261/12505
ISSN: 00408972


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