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In this study, we investigate the relationship between topological and seismological parameters of earthquake sequences generated by the Olami-Feder-Christensen (OFC) [Olami et al., Phys. Rev. Lett. 68(8), 1244 (1992)] spring-block model and converted in undirected graphs by using the visibility graph method [Lacasa et al., Proc. Natl. Acad. Sci. U.S.A. 105(13), 4972-4975 (2008)]. In particular, we study the relationship between the Gutenberg-Richter b-value and the so-called K-M slope, which describes the relationship between magnitudes and connectivity degrees. This relationship was found to follow a rather universal law in observational earthquake sequences, and, thus, in the present work, we aim at verifying such universality also in earthquake sequences generated by the OFC spring-block model. We found that for 〈b〉 between approximately 1 and 2, which is nearly the range of variation for most of the real seismicity cases observed worldwide, the relationship between 〈b〉 and 〈K-M slope〉 does not depend on the lattice size L. Furthermore, the slope of the regression line between 〈b〉 and 〈K-M slope〉 in the range of 〈b〉 between 1 and 2 changes with the definition of magnitude and the length of the earthquake sequence. © 2020 Author(s).

In the framework of S3 project "Short term earthquake forecasting" supported by Department of Civil Protection (DPC) and National Institute of Geophysics and Volcanology (INGV), a magnetotelluric (MT) station was installed in the Pollino area (southern Italy) during September 2012 by the Institute of Methodologies for Environmental Analysis (IMAA-CNR, Italy) in order to investigate possible correlation between electromagnetic signals and seismicity. For the last two years Pollino area has been characterized by swarm-type seismicity, culminating with the earthquake occurred on October 25, 2012 of magnitude M-W=5.0. After the mainshock, the INGV installed a seismic station close to the MT station. In this paper, we focus the analysis on the largest event (M-L=3.6) recorded during the co-located electromagnetic and seismic experiment. We applied time-frequency misfit criteria based on the continuous Morlet wavelet transform to compare the electric and seismic homologous components: this analysis confirms an overall good waveform similarity between the signals, but also some interesting differences in amplitude for frequencies above 1 Hz in correspondence of the arrival of particular seismic phases that need further investigations.

We investigate the time dynamics of sequences of earthquakes occurred in three different seismic zones in Italy. All the series analyzed present 1/f(alpha) temporal fluctuations, shown by the power-law behaviour of several statistics (Fano Factor, Allan Factor and Count-based Periodogram), that allow to detect correlation properties in point processes.

Review of historical and current data on the locations and status of seagrass beds, coralligenous and maerl beds in different GSAs (Geographic Sub Areas)all over the Mediterranean basin

The occurrence of intense CO 2 degassing processes generating hundreds of cold CO 2-rich gas emissions is typical of the central Apennines. In 2009, significant anomalies were detected coinciding with the L'Aquila seismic sequence as a consequence of a wide degassing process. Over the same time-span, space-time anomalies in Thermal InfraRed (TIR) satellite imagery possibly related to the increase of green-house gas (such as CO 2, CH 4, etc.) emission rates were detected in central Italy during the seismic swarm by a Robust Satellite Technique (RST) data analysis. A gas geochemical survey carried out in the L'Aquila area confirms the deep crustal origin of the anomalous gas emission detected by ground measurements. Anomalous fluid related signals were recorded some days before the mainshock coinciding with the most marked TIR anomalies independently detected by the RST analysis over 3 different types of satellite data. Anomalous gas emissions detected by ground measurements lasted some weeks, putting in evidence relationships with crustal deformative processes associated with the seismic sequence. Together with previous ground observations in the Umbria-Marche area, present ground and satellite TIR observations, are compatible with the hypothesis that a central Apennines area, much wider than the L'Aquila (March-April 2009) epicentral one, was actually affected by anomalous increases in CO 2 release thus providing new tools to better understand the processes occurring behind a seismic shock.

The Central Apennines are affected by frequent earthquakes of moderate magnitude that occur mainly within the upper part of the crust at depths of

The interevent-time (IET) and interevent-distance (IED) series of seismic events occurred at Aswan area (Egypt) from 2004 to 2010 were investigated by means of the Fisher Information Measure and the Shannon entropy. The analysis was performed varying the depth and the magnitude thresholds. The results point out to an increase of level of organization and order with the decrease of magnitude threshold and the increase of depth threshold for the IET series, while the IED series are characterized by a level of uncertainty approximately constant with the threshold magnitude. The complexity measure, calculated as the product of the Fisher Information Measure and the Shannon entropy power, presents very similar pattern for both the types of seismic series, indicating an increasing complexity with the decrease of the threshold magnitude and the increase of the threshold depth.

The Fisher-Shannon (FS) information plane, defined by the Fisher information measure (FIM) and the Shannon entropy power (Nx), was robustly used to investigate the complex dynamics of 8 long monthly rainfall time series in central Argentina, recorded from 1860 to 2006. In the FS plane, the rainfall series seem to aggregate into three different clusters corresponding to three different climatological regimes in central Argentina. Our findings suggest the use of the statistical quantity defined by the FS information plane as a tool to discriminate among different climatological regimes. Fil: Pierini, Jorge Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina Fil: Scian, Beatriz Viviana. Universidad Nacional del Sur; Argentina Fil: Lovallo, M.. ARPAB; Italia Fil: Telesca L. Institute of Methodologies for Environmental Analysis; Italia

The Fisher-Shannon information (FS) plane, defined by the Fisher information measure (FIM), and the Shannon entropy power, N (x) , is a robust tool for investigating the complex dynamics of time series. In the FS plane, earthquakes and quarry blasts measured in V,rtes Hills (Hungary) are significantly discriminated from each other. Furthermore, the results of the receiving-operating characteristics (ROC) analysis reveal that FIM is a classifier more efficient than N (x) in discriminating earthquakes from quarry blasts.

Fractal tools are used to investigate the hourly time fluctuations of the ceiling height of a chamber located in the medieval Jeronym Mine, which is one of the Cultural National Heritage sites of the Czech Republic. The data were measured from 2008 to 2010 by a laser distance meter (Leica DISTO (TM) A4). The scaling behavior is revealed by means of different statistics: the power spectrum method, the detrended fluctuation analysis, the Higuchi analysis and the mean distance spanned within time L. The values of the scaling exponents estimated by means of these methods indicate that the temporal fluctuations of the ceiling height are not typical of a purely random stochastic process (i.e. white noise), but evidence the presence of long-range correlations. Furthermore, it is found that these correlations are linear.

The one-, two-and three-dimensional multifractal detrended fluctuation analysis (MF-DFA) was applied to Bach's Sinfonias, which are characterized by the superposition of three different voices. Each voice, represented as a time series, can be considered as a component of a one-, two-or three-dimensional vector. The one-dimensional MF-DFA was applied to any single voice, while the two-and three-dimensional MF-DFA was applied to the couples of voices and to the triple, respectively. Each voice is characterized by a multifractal degree (MD), indicated by the range of the generalized Hurst exponents; the higher the MD, the larger the amount of heterogeneity and irregularity. Competitive scaling multifractal behaviours in Bach's Sinfonias were revealed; although one (or two) voices showed a relatively high MD, the other two voices, or voice, are characterized by a low MD. Nevertheless, the overall effect of the Sinfonia, measured by the MD of the triple, tends towards homogeneity, or at least to an average between the different competitive scaling behaviour shown by the different voices.

The time structure of more than 10 years of hourly wind data measured at one site in northern Italy from April 1996 to December 2007 is analysed. The data were recorded by the Sodar Rass system, which measures the speed and the direction of the wind at several heights above the ground level. To investigate the wind speed time series at seven heights above the ground level we used two different approaches: (i) multifractal detrended fluctuation analysis (MF-DFA), which permits the detection of multifractality in nonstationary series, and (ii) the Fisher-Shannon (FS) information plane, which allows the discrimination of dynamical features in complex time series. Our results point to the existence of multifractal time fluctuations in wind speed and to a dependence of the results on the height of the wind sensor. Even in the FS information plane a height-dependent pattern is revealed, indicating a good agreement with the multifractality. The obtained results could contribute to a better understanding of the complex dynamics of wind phenomena.

The Fisher-Shannon (FS) information plane, defined by the Fisher information measure (FIM) and the Shannon entropy power (Nx), was robustly used to investigate the complex dynamics of 8 long monthly rainfall time series in central Argentina, recorded from 1860 to 2006. In the FS plane, the rainfall series seem to aggregate into three different clusters corresponding to three different climatological regimes in central Argentina. Our findings suggest the use of the statistical quantity defined by the FS information plane as a tool to discriminate among different climatological regimes.

Time-scaling scale-invariant approaches have been used to feature the temporal distribution of city fire sequences recorded in the city of AnShan (China). Our findings reveal that the point process of the city fires is a fractal process with a high degree of time-clusterization of the events. The time-clustering phenomenon is visible for timescales larger than few hours. Furthermore, the fire process tends to be less time-clusterized with the increase of the loss. The application of multifractal detrended fluctuation analysis to the series of city-fires has revealed that the sequence is dynamically heterogeneous due to the different long-range time correlation properties for small and large interevent fluctuations.

Nonextensive statistics has been becoming a very useful tool to describe the complexity of dynamic systems. Recently, analysis of the magnitude distribution of earthquakes has been increasingly used in the context of nonextensivity. In the present paper, the nonextensive analysis of the southern California earthquake catalog was performed. The results show that the nonextensivity parameter q lies in the same range as obtained for other different seismic areas, thus suggesting a sort of universal character in the nonextensive interpretation of seismicity.

We suggest an innovative distribution function of landslide sizes, based on the non-extensive Tsallis entropy. Our result incorporates the characteristics of non-extensivity of fragmentation into the cumulative distribution of landslide sizes. Such an approach can lead to a groundbreaking statistical physics of landslides.

The time-clustering behavior of the 1996-2005 seismicity of Koyna-Warna region (India), a unique site where reservoir-triggered earthquakes have been continuously occurring over the last about 50 year, has been analyzed. The scaling exponent alpha, estimated by using the Allan Factor method, a powerful tool to investigate clusterization in point processes, shows co-seismic and pre-seismic enhancements associated with the occurrence of the major events.