40. Development of the Frequency Distribution of Earthquakes with Respect to the Magnitude in the Aftershocks of the 1968 Tokachi-Oki Earthquake
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Several regularities are revealed for the development of the freqnency distribution of aftershocks with respect to the magnitude in the 1968 Tokachi-Oki earthquake. The main results are as follows. 1) The major aftershocks occur first and then smaller aftershocks are generated. This is the characteristics of the main shock type earthquake. 2) The major aftershocks occur in the early stage of the aftershock activity so as to satisfy Gutenberg-Richter's statistical formula which will be regulated by the principal shock. 3) Smaller aftershocks which are excited by a certain major aftershock occur so as to satisfy the statistical formula by themselves. 4) In the later stage of the aftershock development, aftershocks of intermediate size, with magnitudes around M=6 in this case, occur so as to unify the two populations of smaller earthquakes and major aftershocks to a single earthquake population governed by the principal shock. The correspondence of these characteristics to the development of the aftershock area will be studied in the accompanying paper. The existence of such regularity in the time sequence is another evidence of the fact that Gutenberg and Richter's statistical formula is a physical law and is not a probability distribution.|1968年十勝沖地震の余震においてマグニチュード別度数分布の発達にいくつかの規則性が認められる.主な結果は次の通りである.(1)主な余震が先づ発生し,次に小さい余震が発生する.これは主震型地震の特徴であろう.(2)主な余震は余震活動の早い時期に発生し,主震で規定されるところのGutenberg-Richterの統計式を満たすように起る.(3)或る主な余Uﾐ;こよって誘起される小さい余震は,それ自身でGutenberg-Richterの統計式を満たすように起る.(4)余震活動発達の後期において,中間的規模の地震が起り,小さい余震の母集団と主震および主な余震の母集団の2つを1つの母集団に統一するように起る.これらのマグニチュード別度数分布発達についての特徴が余震域の発達といかに対応するかという問題は次の論文にて取扱われている.マグチュード別度数分布が時間系列において,このように規則性があるということは,統計式が物理法則を表すものであって,確率分布ではたいことのもう1つの証拠であろう.
雑誌名
東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo
巻
48
号
5
ページ
749 - 758
発行年
1970-12-05
ISSN
00408972
書誌レコードID
AN00162258
フォーマット
application/pdf
日本十進分類法
453
出版者
東京大学地震研究所
出版者別名
Earthquake Research Institute, University of Tokyo
40. Development of the Frequency Distribution of Earthquakes with Respect to the Magnitude in the Aftershocks of the 1968 Tokachi-Oki Earthquake
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