TY - JOUR TI - Natural-time analysis of critical phenomena: The case of seismicity AU - Varotsos, P. A. AU - Sarlis, N. V. AU - Skordas, E. S. AU - Uyeda, S. and AU - Kamogawa, M. JO - Europhysics Letters (EPL) PY - 2010 VL - 92 TODO - 2 SP - null PB - IOP Publishing Ltd SN - null TODO - 10.1209/0295-5075/92/29002 TODO - null TODO - 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 kappa(1) = - (2) of natural time chi, 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 kappa(1) approximate to 0.070 was reached. Copyright (C) EPLA, 2010 ER -