  If we assume that earthquakes are chaotic, and influenced locally then chaos
theory suggests that there should be a temporal association between earthquakes
in a local region that should be revealed with statistical examination. To date
no strong relationship has been shown (refs not prediction). However,
earthquakes are basically failures of structured material systems, and when
multiple failure mechanisms are present, prediction of failure is strongly
inhibited without first separating the mechanisms. Here we show that by
separating earthquakes statistically, based on their central tensor moment
structure, along lines first suggested by a separation into mechanisms
according to depth of the earthquake, a strong indication of temporal
association appears. We show this in earthquakes above 200 Km along the pacific
ring of fire, with a positive association in time between earthquakes of the
same statistical type and a negative association in time between earthquakes of
different types. Whether this can reveal either useful mechanistic information
to seismologists, or can result in useful forecasts remains to be seen.
