Non-extensive statistical physics applied to heat flow and the earthquake frequency–magnitude distribution in Greece

Abstract

This study investigates seismicity in Greece and its relation to heat flow, based on the science of complex systems. Greece is characterised by a complex tectonic setting, which is represented mainly by active subduction, lithospheric extension and volcanism. The non-extensive statistical physics formalism is a generalisation of Boltzmann–Gibbs statistical physics and has been successfully used for the analysis of a variety of complex systems, where fractality and long-range interactions are important. Consequently, in this study, the frequency–magnitude distribution analysis was performed in a non-extensive statistical physics context, and the non-extensive parameter, qM, which is related to the frequency–magnitude distribution, was used as an index of the physical state of the studied area. Examination of the spatial distribution of qM revealed its relation to the spatial distribution of seismicity during the period 1976–2009. For focal depths ≤40 km, we observe that strong earthquakes coincide with high qM values. In addition, heat flow anomalies in Greece are known to be strongly related to crustal thickness; a thin crust and significant heat flow anomalies characterise the central Aegean region. Moreover, the data studied indicate that high heat flow is consistent with the absence of strong events and consequently with low qM values (high b-values) in the central Aegean region and around the volcanic arc. However, the eastern part of the volcanic arc exhibits strong earthquakes and high qM values whereas low qM values are found along the North Aegean Trough and southwest of Crete, despite the fact that strong events are present during the period 1976–2009 in both areas.