Renormalization of earthquake aftershocks

Sornette, Anne and Sornette, Didier (1999) Renormalization of earthquake aftershocks. Geophysical Research Letters, 26 (13). pp. 1981-1984. DOI: https://doi.org/10.1029/1999GL900394

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Official URL: http://dx.doi.org/10.1029/1999GL900394

Abstract

Assume that each earthquake can produce a series of aftershock independently of its size according to its “local” Omori's law with exponent 1 + θ. Each aftershock can itself trigger other aftershocks and so on. The global observable Omori's law is found to have two distinct power law regimes, the first one with exponent p− = 1-θ for time t < t* ∼ κ^(−1/θ), where 0 < 1 − κ < 1 measures the fraction of triggered earthquakes per triggering earthquake, and the second one with exponent p+ = 1 + θ for larger times. The existence of these two regimes rationalizes the observation of Kisslinger and Jones [1991] that the exponent p seems positively correlated to the surface heat flow: a higher heat flow is a signature of a higher crustal temperature, which leads to larger strain relaxation by creep, corresponding to fewer events triggered per earthquake, i.e. to a larger κ, and thus to a smaller t*, leading to an effective measured exponent more heavily weighted toward p+ > 1.

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Item Type: Article
Subjects: Methodology > Method and procesing > Collective properties of seismicity > Clustering and migration
Project: IS-EPOS project