There is a news article on the 22 April "Science" on clusters of megaquakes: one set from 1950 to 1965 and the other from late 2004 to present. It said that after 36 there were 36 years with no quake larger than M8.4 One group thinks the clusters are significant, with 2% chance they are random, which would give 63% if a M9 or larger quake in next 6 years. If random, the odds are 24%.

Some of you were discussing this earlier (was it Beth?).
Chris