Applying a simple general procedure for identifying aftershocks, we inves- tigate their statistical properties for a high-resolution earthquake catalog covering South- ern California. We compare our results with those obtained by using other methods in order to show which features truly characterize aftershock sequences and which depend on the definition of aftershocks. Features robust across methods include the p-value in the Omori-Utsu law for large mainshocks, B ̊ath’s law, and the productivity law with an exponent smaller than the b-value in the Gutenberg-Richter law. The identification of a typical aftershock distance with the rupture length is a feature we confirm as well as a power law decay in the spatial distribution of aftershocks with an exponent less than 2. Other results we obtain, but not common to all other works including Marsan and Lenglin ́e [2008]; Hainzl and Marsan [2008]; Zhuang et al. [2008], are (a) p-values that do not increase with the mainshock magnitude, (b) the duration of bare aftershock se- quences that scales with the mainshock magnitude, (c) an additional power-law in the temporal variation, at intermediate times, in the rate of aftershocks for mainshocks of small and intermediate magnitude and (d) a b-value for the Gutenberg-Richter law of background events that is sensibly larger than that of aftershocks. Tests on synthetic cat- alogues generated by the epidemic-type aftershock sequence model corroborate the va- lidity of our approach.

Triggering cascades and statistical properties of aftershocks

BAIESI, MARCO;
2013

Abstract

Applying a simple general procedure for identifying aftershocks, we inves- tigate their statistical properties for a high-resolution earthquake catalog covering South- ern California. We compare our results with those obtained by using other methods in order to show which features truly characterize aftershock sequences and which depend on the definition of aftershocks. Features robust across methods include the p-value in the Omori-Utsu law for large mainshocks, B ̊ath’s law, and the productivity law with an exponent smaller than the b-value in the Gutenberg-Richter law. The identification of a typical aftershock distance with the rupture length is a feature we confirm as well as a power law decay in the spatial distribution of aftershocks with an exponent less than 2. Other results we obtain, but not common to all other works including Marsan and Lenglin ́e [2008]; Hainzl and Marsan [2008]; Zhuang et al. [2008], are (a) p-values that do not increase with the mainshock magnitude, (b) the duration of bare aftershock se- quences that scales with the mainshock magnitude, (c) an additional power-law in the temporal variation, at intermediate times, in the rate of aftershocks for mainshocks of small and intermediate magnitude and (d) a b-value for the Gutenberg-Richter law of background events that is sensibly larger than that of aftershocks. Tests on synthetic cat- alogues generated by the epidemic-type aftershock sequence model corroborate the va- lidity of our approach.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2812881
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