|MadSci Network: Earth Sciences|
As you know, the Richter scale indicates the energy released by an earthquake, approximately. This is roughly the base 10 logarithm of the maximum amplitude of ground motion where the earthquake happened so if you can convert your simulation results to ground motion you will be able to calculate "your own" Richter values. Without more information on how your simulation works I can't offer more specific suggestions. One thought: It might be more instructive to sum over the entire event the square of the amplitude at 1/100th sec intervals (for example) to record the total energy released. Richter and other seismic energy scales are pretty complicated -- as are earthquakes -- so you might make good progress by reading the USGS web site, beginning for example here: http://earthquake.usgs.gov/learning/faq.php?categoryID=2
Try the links in the MadSci Library for more information on Earth Sciences.