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On the size of the strained region prior to an extreme earthquake

Bullen, K. E. (1955) On the size of the strained region prior to an extreme earthquake. Bulletin of the Seismological Society of America, 45 (1). pp. 43-46. ISSN 0037-1106.

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A previous formula of the author's has been adapted to give the volume V of the region in which the material is near breaking-point, just prior to an extreme earthquake, in terms of the released energy and breaking-strength near the focus. In the light of recent earthquake energy-magnitude data of Gutenberg, Richter, and Benioff, it is inferred that V is at least of the order of the volume of a sphere of radius 25 km. Comparison with other estimates of the size of strained regions in earthquakes suggests that V may possibly reach the order of the volume of a sphere of radius 50 km. It is suggested that a factor in the occurrence of extreme earthquakes is the existence, in the zone of strain, of strength rather greater than in the majority of major earthquakes of magnitude one unit or more less than the extreme value.

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Additional Information:Copyright © 1955, by the Seismological Society of America. Manuscript received for publication April 8, 1954. Finally, the writer wishes to thank Professors Gutenberg and Benioff for helpful discussion on various points in this paper, and for the use of the facilities of the Seismological Laboratory of the California Institute of Technology; and the United States Educational Foundation in Australia for kindly providing assistance in the form of a travel grant to California.
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United States Educational Foundation, AustraliaUNSPECIFIED
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Caltech Division of Geological Sciences667
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ID Code:48026
Deposited By: George Porter
Deposited On:06 Aug 2014 14:42
Last Modified:03 Oct 2019 06:59

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