Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 12 1 2005 10.5194/npg-12-83-2005 http://www.nonlin-processes-geophys.net/12/83/2005/ http://www.nonlin-processes-geophys.net/12/83/2005/npg-12-83-2005.html http://www.nonlin-processes-geophys.net/12/83/2005/npg-12-83-2005.pdf 83 88 2005-01-25 On the separation of timescales in spring-block earthquake models S. Hergarten F. Jansen Institute of Geology, University of Bonn, Germany One of the most widespread spring-block earthquake models, the Olami-Feder-Christensen model, is investigated without making the assumption that the duration of individual earthquakes is negligible. While the Gutenberg-Richter law for the size distribution of earthquakes is preserved qualitatively for earthquakes of finite duration, the b-value decreases with increasing earthquake duration. The effect decreases with increasing lattice size, although it is not clear whether it completely vanishes in the limit of infinite grid size. For realistic values of earthquake duration, the effect is negligible, so that the original model with zero earthquake duration is appropriate for most applications.