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タイトル: Some Discussions on Aftershocks, Foreshocks and Earthquake Swarms : the Fracture of a Semi-infinite Body Caused by an Inner Stress Origin and Its Relation to the Earthquake Phenomena (Third Paper)
その他のタイトル: 余震,前震,群発地震の起こりかた : 半無限体の内部力源による破壊およびそれに関連した地震発生のニ,三の問題(第3報)
著者: Mogi, Kiyoo
発行日: 1963年9月30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41冊第3号, 1963.9.30, pp. 615-658
抄録: In the preceding papers40', the patterns of the successive occurrence of elastic shocks accompanying fractures under a simple stress state have been experimentally investigated and they have been classified into three types. The type of shock sequence is decidedly influenced by the mechanical structure of model materials. In this paper, this experimental conclusion has been applied to earthquakes in and near Japan (1926-1961). The main results are summarized as follows. (1) The patterns of earthquake sequences are also classified into the three types which were obtained in the patterns of shock sequences, but the transition from one to another is continuous. (2) About 60 earthquakes preceded by foreshocks (the second type)'have been found. They distribute in groups at certain regions. In such regions where the normal sequence of foreshocks is expected, the seismic- observations may give a clue for prediction of major earthquakes. (3) The regions where a certain type of earthquake sequence frequently appears distribute following a general tendency. The various patterns of earthquake sequences are related to the various degrees of heterogeneity in structure. Thus, the spatial distribution of the regions fractured in various degrees are deduced from the data of the patterns of earthquake sequences. (4) The probability P that an earthquake is followed by aftershocks increases with the magnitude and decreases with the focal depth. Furthermore, the P value varies remarkably in various regions. The spatial distribution of the regions having a high P value of aftershock occurrence is nearly identical to that of the second type and the third type. These regions are also the regions which are fractured to some degree. (5) The spatial distribution of fractured regions deduced from the types of the pattern of earthquake sequences has close relations to various geotectonic structures of the Japanese islands, and to other geophysical data.
前回までに,破壊に伴うElastic shocksの代表的な発生型として三つの型があり,それが主として媒質の構造的不均一さによることを示した(Fig.2).このことは自然地震の場合にも成り立つとの観点から,本論では日本附近に発生した主なる地震の起こり方を組織的に調査,分類して,その発生の機構および日本列島の地体構造との関係を考察した.その主なる結果を次に要約する.(1)日本附近に起こつた地震を上に述べた三つの型に分類して,各型の地理的分布を求めた.また,各地域について,それぞれの発生型のあらわれる確率を求めて,その地理的分布を求めた.これらの分布には,一定の規則比が認められ,日本列島の地体構造と密接な関係を示している.
URI: http://hdl.handle.net/2261/12129
ISSN: 00408972


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