A forward test of the Decelerating–Accelerating Seismic Strain model to western south and central America

Global observations show that strong mainshocks are preceded by decelerating preshocks which occur in the focal (seismogenic) region of the ensuing mainshock and by accelerating preshocks which occur in a broader (critical) region of the mainshock. Predictive properties of these preshocks have been expressed by empirical relations supported by theory and form the Decelerating–Accelerating Seismic Strain (D–AS) model. A respective algorithm has been developed which is used to identify the critical and seismogenic region and estimate (predict) the corresponding ensuing mainshock. In the present work a forward test of this model is performed by attempting intermediate-term prediction of future big (M ≥ 7.7) mainshocks along the western coast of south and central America. Three regions of decelerating shocks and three corresponding regions of accelerating shocks have been identified. The parameters (origin time, magnitude, epicenter coordinates) as well as their uncertainties have been estimated (predicted) for the corresponding probably ensuing three mainshocks. This forward test allows an objective evaluation of the model's ability for an intermediate-term prediction of strong shallow mainshocks.