From the history of physics

Omori's law: a note on the history of geophysics

Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences, Bolshaya Gruzinskaya ul. 10, Moscow, 123995, Russian Federation

In the late nineteenth century, the Japanese seismologist Omori discovered the first law of earthquake physics, which states that the rate of aftershocks decreases hyperbolically with time. Over the years since then, there has been a vast literature on this law, and the significance of its discovery has been universally recognized. There is, however, profound division of opinion as to the interpretation of the law. Some argue that Omori just proposed a simple data-fitting formula and replace this formula by a power law one with a negative fractional exponent, whereas for others, the Omori law makes physical sense. The paper describes history and essence of Omori?s discovery, with special attention paid to interpretational questions. It is shown that Omori?s original formulation of the law quite correlates with the current understanding of the rock destruction mechanism at the earthquake focus.

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Keywords: seismology, earthquake, aftershock, tectonic fault, recombination, relaxation
PACS: 91.30.−f
DOI: 10.3367/UFNe.2017.01.038039
Citation: Guglielmi A V "Omori's law: a note on the history of geophysics" Phys. Usp. 60 319–324 (2017)
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Received: 30th, July 2016, revised: 22nd, December 2016, 17th, January 2017

Оригинал: Гульельми А В «Закон Омори (из истории геофизики)» УФН 187 343–348 (2017); DOI: 10.3367/UFNr.2017.01.038039

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