Critical behaviour of seismic systems and dynamics in ensemble of strong earthquakes

Abstract

We present the basic regularities that govern the time evolution dynamics of earthquakes in the seismic system (SS) defined as a unique active volume of lithosphere responsible for preparation of strong earthquakes above a certain threshold magnitude. This concept was articulated previously within phenomenological approach of seismic entropy which utilizes real-time monitoring of strong earthquakes. Seismic parameters such as cumulative energy, number of seismic system states and entropy are calculated to reliably describe in real space- time the non-equilibrium dynamics of the active volume of the Earth's lithosphere. The behaviour of seismic parameters also shows the direction of tectonic processes which preserve a long-term memory of all previously released energies of preceding earthquakes as well as the time when they occurred. The obtained power-law relationship between the information entropy and cumulative energy within a cycle implies that seismically ideal homogeneous system over time tends to the certain critical conditions (attractor). The well-defined SS forms an ensemble of strong earthquakes with critical instabilities which periodically restore the equilibrium state of the system. The finite size of SS and minimal unit of microquake leads to selectivity and discreteness of the earthquake magnitude. It is found that indicator earthquakes above certain threshold magnitudes at which the Gutenberg-Richter law is often violated, play a crucial role in preparation of strong earthquakes. The calculated trajectory diagrams describing the dynamic evolutions of lithosphere allow construct the attractor for real SSs by solving the inverse problem. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.