Suchergebnisse

Abstract. 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.

Abstract. We studied the time fluctuations in the dynamics of geoelectrical data, recorded in Tito site, which is located in a seismic area of southern Italy. We used the Fisher Information Measure, which is a powerful tool to investigate complex and nonstationary signals. The time evolution of the Fisher Information Measure calculated for our signal reveals links with the earthquakes occurring in the investigated area.

Abstract. We investigated by means of nonlinear tools the temporal distribution of 1983-2003 seismicity of the Umbria-Marche region, Central Italy, that was struck by a strong event (M=5.8) on 26 September 1997. Information entropy analysis has been performed over the full and the aftershock-depleted catalogue. We analysed the series of the interevent times between successive earthquakes and the series of their magnitudes. The time evolution of this measure shows a clear anomalous behaviour in correspondence with the stronger event, more evident in the full catalogue than in the aftershock-depleted one.

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.