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Non-extensive statistical physics analysis of earthquake magnitude sequences in North Aegean Trough, Greece

Papadakis G., Vallianatos F.

Acta Geophysica

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2017

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Vol. 65, no. 3

555--563

EN

In a recent study, Papadakis et al. (Physica A 456: 135–144, 2016) investigate seismicity in Greece, using the non-extensive statistical physics formalism. Moreover, these authors examine the spatial distribution of the non-extensive parameter qM and show that for shallow seismicity, increase of qM coincides with strong events. However, their study also reveals low qM values along the North Aegean Trough, despite the presence of strong events during 1976–2009. Consequently, the present study further examines the temporal behaviour of parameters qM and A, to reveal their relation with the evolution of the earthquake sequence. Through temporal examination of these parameters, we aim to show that the seismogenic system of the North Aegean Trough presents high degree of interactions after strong earthquakes during the studied period. Our findings indicate that increase of qM signifies the existence of long-range correlations. If its value does not significantly decrease after a strong earthquake (i.e. M ≥ 5) then the studied area has not reached the state of equilibrium.

2

Statistical mechanics in earth physics and natural hazards

Vallianatos F., Telesca L.

Acta Geophysica

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2012

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Vol. 60, no. 3

499-501

3

Experimental evidence of a non-extensive statistical physics behavior of electromagnetic signals emitted from rocks under stress up to fracture. Preliminary results

Vallianatos F., Nardi A., Carluccio R., Chiappini M.

Acta Geophysica

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2012

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Vol. 60, no. 3

894-909

EN

The application of mechanical stress on a rock sample can induce electromagnetic emissions. Such emissions can be detected experimentally and in principle could be used as precursors of the upcoming failure. Using experimental observations of stress-induced electromagnetic emissions (SIEME), we apply the concepts of non-extensive statistical physics (NESP) to the time intervals between consecutive SIEME. The application of NESP is appropriate to systems such as fracture-induced effects, where non-linearity, long-range interactions and scaling are important. We find that the SIEME energy release distribution and the inter-event time distribution reflect a sub-extensive system with thermodynamic q-values of the order of qE = 1.67 and qτ ≈ 1.7, respectively.

4

Emulation of simulated earthquake catalogues

Gallucci M., Guillas S., Vallianatos F.

Acta Geophysica

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2012

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Vol. 60, no. 3

699-718

EN

In earthquake occurrence studies, the so-called q value can be considered both as one of the parameters describing the distribution of inter-event times and as an index of non-extensivity. Using simulated datasets, we compare four kinds of estimators, based on principle of maximum entropy (POME), method of moments (MOM), maximum likelihood (MLE), and probability weighted moments (PWM) of the parameters (q and τ0) of the distribution of inter-events times, assumed to be a generalized Pareto distribution (GPD), as defined by Tsallis (1988) in the frame of non-extensive statistical physics. We then propose to use the unbiased version of PWM estimators to compute the q value for the distribution of inter-event times in a realistic earthquake catalogue simulated according to the epidemic type aftershock sequence (ETAS) model. Finally, we use these findings to build a statistical emulator of the q values of ETAS model. We employ treed Gaussian processes to obtain partitions of the parameter space so that the resulting model respects sharp changes in physical behaviour. The emulator is used to understand the joint effects of input parameters on the q value, exploring the relationship between ETAS model formulation and distribution of inter-event times.

5

A non-extensive statistical physics view to the spatiotemporal properties of the June 1995, Aigion earthquake (M6.2) aftershock sequence (West Corinth rift, Greece)

Vallianatos F., Michas G., Papadakis G., Sammonds P.

Acta Geophysica

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2012

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Vol. 60, no. 3

758-768

EN

In the present study, the spatiotemporal properties of the Aigion earthquake (15 June 1995) aftershock sequence are being studied using the concept of non-extensive statistical physics (NESP). The cumulative distribution functions of the inter-event times and the inter-event distances are being estimated for the data set which is assumed to be complete and the analysis yielded the thermodynamic q parameter to be qT = 1.58 and qr = 0.53 for the two distributions, respectively. The results fit rather well to the inter-event distances and times distributions, implying the complexity of the spatiotemporal properties of seismicity and the usefulness of NESP in investigating such phenomena. The temporal structure is also being discussed using the complementary to NESP approach of superstatistics, which is based on a superposition of ordinary local equilibrium statistical mechanics. The result indicates that very low degrees of freedom describe the temporal evolution of the Aigion earthquake aftershock seismicity.

6

Non-extensive statistical physics approach to fault population distribution. A case study from the southern Hellenic arc (Central Crete)

Vallianatos F., Kokinou E., Sammonds P.

Acta Geophysica

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2011

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Vol. 59, no. 4

770-784

EN

Fault population statistics play a key role in the understanding of any statistical seismicity approach. In the present work a non-extensive statistical physics approach is formulated and tested for the local fault length distribution. The approach is composed of the following parts: (i) Tsallis entropy, Sq , (ii) maximization of the Tsallis entropy under appropriate constrains, and (iii) derivation of the cumulative distribution function (CDF) of the fault length population. This model is tested using fault length data from the Central Crete graben in front of the Hellenic arc and estimated a thermodynamic q parameter equal to 1.16, which supports the conclusion that the fault system in Central Crete graben is a sub-extensive one.