As I've always said, something is very weird about this earthquake. I'm saying it's a 'hard rock' complex earthquake, that rupture in distinct sections. The maximum section was probably an M6.0, in terms of strong ground motions, which were about 1-2 cm/s on firm ground. There were no near-field recordings on firm ground.
Since the instrumentation was inadequate to resolve this, we can look at the aftershock sequence. On one hand, we have this article, which says everything is perfectly normal for an M7.1. For those of you who believe the official line, you can stop here. :)
However, for an M7.1, I would expect the aftershock sequence to cascade down from an M6.0. Here is a graph from the Parkfield M6.0.
As usual, I'm just relying on my experience, and don't want to engage in any academic hissy fights. :)