Evidence of Non-extensivity in Earth’s Ambient Noise

Koutalonis, Ioannis; Vallianatos, Filippos

doi:10.1007/s00024-017-1669-9

Cited by 12 publications

(5 citation statements)

References 39 publications

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“…In (Koutalonis and Vallianatos, 2017;Vallianatos et al, 2019) the non-extensive entropy of Tsallis was used to analyze seismic noise. The natural time approach to the analysis of random data uses a related definition of entropy in (Varotsos et al, 2003a;Varotsos et al, 2003b;Varotsos et al, 2004;Varotsos et al, 2011).…”

Section: Seismic Noise Statisticsmentioning

confidence: 99%

Investigation of the Global Seismic Noise Properties in Connection to Strong Earthquakes

Lyubushin

2022

Front. Earth Sci.

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The global seismic noise, recorded on a network of 229 broadband seismic stations located around the globe for 25 years, from the beginning of 1997 to the end of 2021, has been investigated. To study the noise properties a set of statistics estimated daily have been used: the multifractal singularity spectrum support width, the minimum entropy of the squared wavelet coefficients, and the wavelet-based Donoho-Johnstone (DJ) index. It is shown that the time points of local extrema of the average values of the analyzed noise properties (minima for singularity spectrum support width and DJ-index and maxima for entropy) tend to occur before strong earthquakes. The time interval from the middle of 2002 to the middle of 2003 is determined, when the trend of decreasing the average coherence of the noise properties in the auxiliary network of 50 reference points changed to an increase. Along with an increase in the average coherence, there is an increase in the radius of the spatial maximum coherences of noise properties. Both of these trends continue until the end of 2021, which is interpreted as a general sign of an increase in the degree of criticality of the state of the planet and, as a result, an increase in global seismic danger. After two mega-earthquakes close in time: 27 February 2010, M=8.8 in Chile and 11 March 2011, M=9.1 in Japan, there was an increase in the spatial scales of the strong coherence of noise parameters, which is a sign of an increase in the critical state. The response of seismic noise properties to variations in the length of the day (LOD) has been studied. An estimate of the correlation function between the mean values of the response to LOD and the logarithm of the released seismic energy in a time window of 1 year indicates a delay in energy release with respect to the maxima of the response of noise properties to LOD with a delay time of about 500 days. In connection with this result, an additional intrigue is the extreme increase in the average value of the response to LOD in 2021.

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Section: Seismic Noise Statisticsmentioning

confidence: 99%

Investigation of the Global Seismic Noise Properties in Connection to Strong Earthquakes

Lyubushin

2022

Front. Earth Sci.

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“…In the natural time approach (Varotsos et al, 2011;Sarlis et al, 2018), the related entropy construction was proposed for data analysis. Application of Tsallis nonextensive entropy to investigating properties of ambient seismic noise was performed in (Koutalonis and Vallianatos, 2017;Vallianatos et al, 2019).…”

Section: Minimum Wavelet-based Normalized Entropymentioning

confidence: 99%

Global Seismic Noise Entropy

Lyubushin

2020

Front. Earth Sci.

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Data of continuous records of low-frequency (periods from 2 to 1,000 min) seismic noise on a global network of 229 broadband stations located around the world for 23 years, 1997–2019, are analyzed. The daily values of the entropy of the distribution of the squares of the orthogonal wavelet coefficients are considered as an informative characteristic of noise. An auxiliary network of 50 reference points is introduced, the positions of which are determined from the clustering of station positions. For each reference point, a time series is calculated, consisting of 8,400 samples with a time step of 1 day, the values of which are determined as the medians of the entropy values at the five nearest stations that are operable during the given day. The introduction of a system of reference points makes it possible to estimate temporal and spatial changes in the correlation of noise entropy values around the world. Estimation in an annual sliding time window revealed a time interval from mid-2002 to mid-2003, when there was an abrupt change in the properties of global noise and an intensive increase in both average entropy correlations and spatial correlation scales began. This trend continues until the end of 2019, and it is interpreted as a feature of seismic noise which is connected with an increase in the intensity of the strongest earthquakes, which began with the Sumatran mega-earthquake of December 26, 2004 (M = 9.3). The values of the correlation function between the logarithm of the released seismic energy and the bursts of coherence between length of day and the entropy of seismic noise in the annual time window indicate the delay in the release of seismic energy relative to the coherence maxima. This lag is interpreted as a manifestation of the triggering effect of the irregular rotation of the Earth on the increase in global seismic hazard.

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“…where f (x) decays as x −α with α = 1.00 and the data collapse is in agreement with the scaling hypothesis, as seen in Fig 2(b). An important point to highlight is that the q-Gaussian distribution appears naturally from the maximization of the Tsallis entropy [32], which is used to explain many complex systems with characteristics such as long-range interaction between its elements and long-range temporal memory, where the traditional Boltzmann-Gibbs statistical mechanics does not seems to apply [33][34][35][36][37][38]. Another point of interest is that a previous work has found the same q-Gaussian behavior for connectivity distributions in networks of epicenters using a modified version of the OFC model, where the small-world effect was taken into account in the lattice topology construction [39].…”

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confidence: 99%

Towards evidence of long-range correlations in shallow seismic activities

Ferreira

Ribeiro

Papa

et al. 2018

EPL

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In this work, we introduce a new methodology to construct a network of epicenters that avoids problems found in well-established methodologies when they are applied to global catalogs of seisms. The new methodology involves essentially the introduction of a time window which works as a temporal filter. Our approach is more generic and for small regions the results coincide with previous findings. The network constructed with that model has small-world properties and the distribution of node connectivity follows a non-traditional q-Gaussian function, where scalefree properties are present. The vertices with larger connectivity in the network correspond to the areas with very intense seismic activities in the period considered. These new results strengthen the hypothesis of long spatial and temporal correlations between earthquakes.

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Evidence of Non-extensivity in Earth’s Ambient Noise

Cited by 12 publications

References 39 publications

Investigation of the Global Seismic Noise Properties in Connection to Strong Earthquakes

Investigation of the Global Seismic Noise Properties in Connection to Strong Earthquakes

Global Seismic Noise Entropy

Towards evidence of long-range correlations in shallow seismic activities

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