Department of Statistics, UCLA

We introduce the use of prototype point patterns to characterize the behavior of a typical aftershock sequence from the global Harvard earthquake catalog. These prototypes are used not only for data description and summary but also to identify outliers and to classify sequences into groups exhibiting similar aftershock behavior. We find that a typical shallow earthquake of magnitude between 7.5 and 8.0 has five aftershocks of magnitude at least 5.5, and these aftershocks are roughly evenly distributed in logtime between 0.113 days and 2.0 years after the mainshock. The relative magnitudes and distances from the mainshock for the typical aftershock sequence are characterized as well.