  Despite the enormous efforts towards searching for precursors, no precursors
have exhibited real predictive power with respect to an earthquake thus far.
Seismogenic locked segments that can accumulate adequate strain energy to cause
major earthquakes are very heterogeneous and less brittle; progressive failures
of the locked segments with these properties can produce an interesting seismic
phenomenon: a characteristic earthquake and a sequence of smaller subsequent
earthquakes (pre-shocks) always arise prior to another characteristic
earthquake within a well-defined seismic zone and its current seismic period.
Applying a mechanical model and magnitude constraint conditions, we show that
two adjacent characteristic earthquakes reliably occur at the volume-expansion
and peak-stress points of a locked segment. Such a seismicity pattern has
occurred in 62 seismic zones worldwide, suggesting that the pattern applies
universally. Both the precursor pattern and the model quantifying it permit the
prediction of certain characteristic earthquakes in a seismic zone.
