  A part of the seismic time series, in which the Omori law for temporal
pattern of aftershocks holds, is refereed to as the Omori regime. Here the
properties of correlation between earthquake events both inside and outside of
the Omori regime are studied by analysis of the data taken in southern
California. It is found that inside of the Omori regime correlation exhibits
the aging phenomenon, in marked contrast to the fact that no aging is observed
outside of the Omori regime. The scaling nature of aging is also discussed and
the form of the function responsible for it is presented. The results indicate
that complex fault-fault interactions may be governed by glassy dynamics.
