Long-term earthquake prediction along the western coast of South and Central America based on a time predictable model

The repeat times,T, of strong shallow mainshocks in fourteen seismogenic sources along the western coast of South and Central America have been determined and used in an attempt at long-term forecasting. The following relation was determined: $$\log T = 0.22M_{\min } + 0.21M_p + a$$ between the repeat time,T, and the magnitudes,M _min, of the minimum mainshock considered andM _p , of the preceding mainshock. No dependence of the magnitude,M _f , of the following mainshock on the preceding intervent time,T, was found. These results support the idea that the time-predictable model is valid for this region. This is an interesting property for earthquake prediction since it provides the ability to predict the time of occurrence of the next strong earthquake. A strong negative dependence ofM _f onM _p was found, indicating that a large mainshock is followed by a smaller magnitude one, andvice versa. The probability for the occurrence of the expected strong mainshocks (M _s ≥7.5) in each of the fourteen seismogenic sources during the next 10 years (1992–2002) is estimated, adopting a lognormal distribution for earthquake interevent times. High probabilities (P ₁₀>0.80) have been calculated for the seismogenic sources of Oaxaca, Chiapas and Southern Peru.