Natural-time analysis of critical phenomena: The case of seismicity
Solid State Section and Solid Earth Physics Institute, Physics Department, University of Athens Panepistimiopolis, Zografos 157 84, Athens, Greece, EU
2 Japan Academy - Ueno Koen, Taitou-ku, Tokyo, 110-0007, Japan
3 Department of Physics, Tokyo Gakugei University - Koganei-shi, 184-8501, Japan
Accepted: 29 September 2010
We first investigate in natural time the numerical simulations of a simple deterministic self-organized critical system introduced to describe avalanches in stick-slip phenomena. It is one-dimensional and belongs to the same universality class as the train model for earthquakes introduced by Burridge and Knopoff. We show that the variance κ1=⟨χ2⟩−⟨χ⟩2 of natural time χ, becomes approximately equal to 0.070 when the system approaches the critical state. Next, we analyze in natural time the small earthquakes subsequent to the low-frequency magnetic-field precursor observed near the epicenter of the Ms7.1 Loma Prieta earthquake in 1989. We find that almost five days before the mainshock, the condition κ1≈0.070 was reached.
PACS: 91.30.Ab – Theory and modeling, computational seismology / 89.75.Da – Systems obeying scaling laws / 95.75.Wx – Time series analysis, time variability
© EPLA, 2010