Failure of self-similarity for large (Mω> 814) earthquakes

We compare teleseismic P-wave records for earthquakes in the magnitude range from 6.0 to 9.5 with synthetics for a self-similar, ω2 source model and conclude that the energy radiated by very large earthquakes (Mw > 814) is not self-similar to that radiated from smaller earthquakes (Mw < 814). Furthermore, in the period band from 2 sec to several tens of seconds, we conclude that large subduction earthquakes have an average spectral decay rate of ω-1.5. This spectral decay rate is consistent with a previously noted tendency of the ω2 model to overestimate Ms for large earthquakes.