Abstract
Abstract. The time dynamics of seismicity of Aswan area (Egypt) from 2004 to 2010 was investigated by means of the (i) Allan Factor, which is a powerful tool allowing the capture of time-clusterized properties of temporal point processes; and the (ii) detrended fluctuation analysis, which is capable of detecting scaling in nonstationary time series. The analysis was performed varying the depth and the magnitude thresholds. The 2004–2010 Aswan seismicity is characterized by significant three-fold time-clustering behaviors with scaling exponents ~0.77 for timescales between 104.16 s and 105.14 s, ~0.34 for timescales between 105.14 s and 106.53 s, and ~1 for higher timescales. The seismic interevent times and distances are characterized by persistent temporal fluctuations for most of the magnitude and depth thresholds.
Highlights
A marked temporal stochastic point process describes events occurring randomly in time (Cox and Isham, 1980) marked by the intensity of the events, and is completely defined by the set of the time occurrences
In order to capture the main characteristics of the time dynamics of a process, the power spectral density (PSD) is the first method to be used because it furnishes information on the frequency distribution of the process power, which is the physical quantity characterizing a process
Periodicities can be revealed by spike-like variations in the PSD, while a power-law shape f −α reveals that the process is scaling; the power-law exponent, called the scaling exponent, conveys qualitative and quantitative information about the type and strength of the temporal fluctuations governing the process
Summary
A marked temporal stochastic point process describes events occurring randomly in time (Cox and Isham, 1980) marked by the intensity of the events, and is completely defined by the set of the time occurrences. Such representation was used in modelling several and diverse point processes, like earthquakes (Telesca and Lovallo, 2009; Telesca et al, 2009a, b), lightning (Telesca et al, 2005), starquakes (Telesca, 2005), solar flares (Telesca, 2007), and some human and social disasters (Telesca and Lovallo, 2006). If the scaling exponent is negative, the PSD behaves as an increasing function of the frequency f ; this indicates that the high-frequency temporal fluctuations are predominant In this case the process is negatively correlated or antipersistent. The antipersistence is a dynamical property of a process in which an increase (decrease) of the process in one period is very likely followed by a decrease
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