Quantifying the M8 prediction algorithm: Reduction to a single critical variable and stability results

Abstract

An implementation of the seven M8 functions within a statistical seismology software library (SSLib) is described. An algorithm is also developed for combining the seven series into a single Critical Series such that a “Time of Increased Probability” (TIP) is declared for the test region whenever the Critical Series passes its threshold level. Values of the Critical Series are plotted for circles on a dense lattice of points covering New Zealand, for each 6 monthly period. The resulting maps can be used to obtain a geographical impression of the evolution of regions close to or far from reaching TIP status according to the criteria embodied in the original M8 algorithm. We examine the stability of the M8 series for small perturbations of the centres of the test regions and the start date of the computations. It is inferred that such instability that is observed in the declaration of TIPs is due more to the use of hard boundaries in the definition of the TIP than to the instability of the component series. © 2003 Taylor & Francis Group, LLC.