Articles | Volume 6, issue 2
Nat. Hazards Earth Syst. Sci., 6, 205–228, 2006

Special issue: Seismic hazard evaluation, precursory phenomena and seismo...

Nat. Hazards Earth Syst. Sci., 6, 205–228, 2006

  03 Apr 2006

03 Apr 2006

Unified approach to catastrophic events: from the normal state to geological or biological shock in terms of spectral fractal and nonlinear analysis

K. A. Eftaxias1, P. G. Kapiris1, G. T. Balasis2, A. Peratzakis1, K. Karamanos3, J. Kopanas1, G. Antonopoulos1, and K. D. Nomicos4 K. A. Eftaxias et al.
  • 1Solid State Section, Physics Department, University of Athens, Panepistimiopolis, 157-84, Zografos, Athens, Greece
  • 2Department of Earth’s Magnetic Field, GeoForschungsZentrum Potsdam, Telegrafenberg, 14473, Potsdam, Germany
  • 3Centre for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles, Campus Plaine, C.P. 231, Boulevard du Triomphe, B-1050, Brussels, Belgium
  • 4Department of Electronics, Technological Education Institute of Athens, Egaleo, 12210, Greece

Abstract. An important question in geophysics is whether earthquakes (EQs) can be anticipated prior to their occurrence. Pre-seismic electromagnetic (EM) emissions provide a promising window through which the dynamics of EQ preparation can be investigated. However, the existence of precursory features in pre-seismic EM emissions is still debatable: in principle, it is difficult to prove associations between events separated in time, such as EQs and their EM precursors. The scope of this paper is the investigation of the pre-seismic EM activity in terms of complexity. A basic reason for our interest in complexity is the striking similarity in behavior close to irreversible phase transitions among systems that are otherwise quite different in nature. Interestingly, theoretical studies (Hopfield, 1994; Herz and Hopfield 1995; Rundle et al., 1995; Corral et al., 1997) suggest that the EQ dynamics at the final stage and neural seizure dynamics should have many similar features and can be analyzed within similar mathematical frameworks. Motivated by this hypothesis, we evaluate the capability of linear and non-linear techniques to extract common features from brain electrical activities and pre-seismic EM emissions predictive of epileptic seizures and EQs respectively. The results suggest that a unified theory may exist for the ways in which firing neurons and opening cracks organize themselves to produce a large crisis, while the preparation of an epileptic shock or a large EQ can be studied in terms of ''Intermittent Criticality''.