NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-8-973-2008 Investigating non-uniform scaling behaviour in temporal fluctuations of seismicity Telesca L. 1 Lovallo M. 1 Dipartimento Infrastrutture e Mobilità, Ufficio Difesa del Suolo, Regione Basilicata, Potenza, Italy 01 09 2008 8 5 973 976 Copyright: © 2008 L. Telesca 2008 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/articles/8/973/2008/nhess-8-973-2008.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/8/973/2008/nhess-8-973-2008.pdf

Scaling behaviour in nonstationary time series can be successfully detected using the detrended fluctuation analysis (DFA). Observational time series often do not show a stable and uniform scaling behaviour, given by the presence of a unique clear scaling region. The deviations from uniform power-law scaling, which suggest the presence of changing dynamics in the system under study, can be identified and quantified using an appropriate instability index. In this framework, the scaling behaviour of the 1981–2007 seismicity in Umbria-Marche (central Italy), which is one of the most seismically active areas in Italy, was investigated. Significant deviations from uniform power-law scaling in the seismic temporal fluctuations were revealed mostly linked with the occurrence of rather large earthquakes or seismic clusters.

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