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Telesca L.,CNR Institute of Methodologies for Environmental analysis | Lovallo M.,ARPAB | Hsu H.-L.,National Central University | Chen C.-C.,National Central University
Physica A: Statistical Mechanics and its Applications | Year: 2011

The FisherShannon information (FS) plane, defined by the Fisher information measure and the Shannon entropy power, is used to investigate the complex dynamics of magnetotelluric data of three stations in Taiwan. In the FS plane the electric and magnetic components are significantly separated, characterized by different degrees of order. Further investigation shows that signals measured in areas with very high level of seismic activity are well discriminated. © 2010 Elsevier B.V. All rights reserved.

Telesca L.,CNR Institute of Methodologies for Environmental analysis | Lovallo M.,ARPAB
Journal of Statistical Mechanics: Theory and Experiment | Year: 2011

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. © IOP Publishing Ltd.

Telesca L.,CNR Institute of Methodologies for Environmental analysis | Lovallo M.,ARPAB
Physica A: Statistical Mechanics and its Applications | Year: 2010

By using the detrended fluctuation analysis and detrended moving average method, 823 time series of tree-ring widths in Austrocedrus Chilensis in Patagonia were analyzed. The tree-ring widths of A. Chilensis have been widely used for climatological studies. The results point out to the presence of significant scaling in the temporal fluctuations of tree-ring, which is not due to singular probability density function of the widths but due to the presence of long-range correlations. Such results are in good agreement with those concerning the evidence of long-range dependencies in weather time series. © 2010 Elsevier B.V. All rights reserved.

Telesca L.,CNR Institute of Methodologies for Environmental analysis | Lovallo M.,ARPAB
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2011

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. This journal is © 2011 The Royal Society.

Lanorte A.,CNR Institute of Methodologies for Environmental analysis | Lasaponara R.,CNR Institute of Methodologies for Environmental analysis | Lovallo M.,ARPAB | Telesca L.,CNR Institute of Methodologies for Environmental analysis
International Journal of Applied Earth Observation and Geoinformation | Year: 2014

The time dynamics of SPOT-VEGETATION Normalized Difference Vegetation Index (NDVI) time series areanalyzed by using the statistical approach of the Fisher-Shannon (FS) information plane to assess andmonitor vegetation recovery after fire disturbance. Fisher-Shannon information plane analysis allowsus to gain insight into the complex structure of a time series to quantify its degree of organization andorder. The analysis was carried out using 10-day Maximum Value Composites of NDVI (MVC-NDVI) witha 1 km × 1 km spatial resolution. The investigation was performed on two test sites located in Galizia(North Spain) and Peloponnese (South Greece), selected for the vast fires which occurred during thesummer of 2006 and 2007 and for their different vegetation covers made up mainly of low shrublandin Galizia test site and evergreen forest in Peloponnese. Time series of MVC-NDVI have been analyzedbefore and after the occurrence of the fire events. Results obtained for both the investigated areas clearlypointed out that the dynamics of the pixel time series before the occurrence of the fire is characterized bya larger degree of disorder and uncertainty; while the pixel time series after the occurrence of the fire arefeatured by a higher degree of organization and order. In particular, regarding the Peloponneso fire, suchdiscrimination is more evident than in the Galizia fire. This suggests a clear possibility to discriminatethe different post-fire behaviors and dynamics exhibited by the different vegetation covers. © 2013 Elsevier B.V.

Aggarwal S.K.,Institute of Seismological Research | Lovallo M.,ARPAB | Khan P.K.,Indian School of Mines | Rastogi B.K.,Institute of Seismological Research | Telesca L.,National Research Council Italy
Physica A: Statistical Mechanics and its Applications | Year: 2015

The sequence of magnitudes of the earthquakes occurred in Kachchh area (Gujarat, Western India) from 2003 to 2012, has been analysed by using the multifractal detrended fluctuation analysis. The complete and the aftershock-depleted catalogues with minimum magnitude M3 were investigated. Both seismic catalogues show multifractal characteristics. The aftershock-depleted catalogue is more multifractal and also more persistent than the whole catalogue; this indicates that aftershock magnitudes contribute to increase the homogeneity and the randomness of the magnitude sequence of the whole seismicity. The singularity spectrum of the whole catalogue, however, is more left-skewed than that of the aftershock-depleted one, indicating a stronger dependence of the multifractality on the large magnitude fluctuations. © 2015 Elsevier B.V. All rights reserved.

Telesca L.,CNR Institute of Methodologies for Environmental analysis | Lovallo M.,ARPAB | Carniel R.,University of Udine
Journal of Volcanology and Geothermal Research | Year: 2010

The investigation of the time dynamics of volcanic tremor recorded at Stromboli volcano before the paroxysm occurred on April 5, 2003 was performed, on the base of a new approach, the Fisher Information Measure (FIM), which allows to detect changes in the dynamical behavior of a complex system. The particular observed pattern suggests that the signal varies between sets of disordered states (small FIM) and sets of ordered states (large FIM). Significant precursory changes in the temporal variation of the FIM were revealed at least 42. h before the paroxysm and lasting about 17. h. The timescales highlighted are compatible to those found by other authors and could qualify the FIM as a good detector of regime changes and possible precursors of anomalous volcanic activity. © 2010 Elsevier B.V.

Czechowski Z.,Polish Academy of Sciences | Lovallo M.,ARPAB | Telesca L.,National Research Council Italy
Chaos | Year: 2016

In this study, we investigate multifractal properties of connectivity time series resulting from the visibility graph applied to normally distributed time series generated by the Ito equations with multiplicative power-law noise. We show that multifractality of the connectivity time series (i.e., the series of numbers of links outgoing any node) increases with the exponent of the power-law noise. The multifractality of the connectivity time series could be due to the width of connectivity degree distribution that can be related to the exit time of the associated Ito time series. Furthermore, the connectivity time series are characterized by persistence, although the original Ito time series are random; this is due to the procedure of visibility graph that, connecting the values of the time series, generates persistence but destroys most of the nonlinear correlations. Moreover, the visibility graph is sensitive for detecting wide "depressions" in input time series. © 2016 AIP Publishing LLC.

Telesca L.,National Research Council Italy | Lovallo M.,ARPAB
EPL | Year: 2012

The seismicity of Italy between April 16, 2005 and December 31, 2010 is investigated by means of the visibility graph method. The degree distribution of the magnitude point process is power-law-shaped. The method does not seem to detect time-clustering structures in the magnitude point process. The degree distribution does not change significantly with the increase of the magnitude threshold from 1.9 to 3.5. The exponent of the degree distribution shows a certain stability vs. the threshold magnitude, ranging between 3.00 and 3.25, with mean value 3.11±0.06. © Europhysics Letters Association, 2012.

Telesca L.,National Research Council Italy | Lovallo M.,ARPAB | Ramirez-Rojas A.,Metropolitan Autonomous University | Flores-Marquez L.,National Autonomous University of Mexico
Physica A: Statistical Mechanics and its Applications | Year: 2013

By using the method of the visibility graph (VG), five magnitude time series extracted from the seismic catalog of the Mexican subduction zone were investigated. The five seismic sequences represent the seismicity which occurred between 2005 and 2012 in five seismic areas: Guerrero, Chiapas, Oaxaca, Jalisco and Michoacán. Among the five seismic sequences, the Jalisco sequence shows VG properties significantly different from those shown by the other four. Such a difference could be inherent in the different tectonic settings of Jalisco with respect to those characterizing the other four areas. The VG properties of the seismic sequences have been put in relationship with the more typical seismological characteristics (b-value and a-value of the Gutenberg-Richter law). © 2013 Elsevier B.V. All rights reserved.

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