What if this tectonic stuff happened during during a sunspot minim? I think that if you go back you can find several earlier events on a roughly 1000 year time line.
Gribbin and Plagemann (sp?) did that book, about 35-40 years ago, "The Jupiter Effect", which claimed that a somewhat superficial review of the data from the previous couple of Grand Alignments of the planets suggested that disastrous, basically apocalyptic quakes occurred (interval something like 178 years, if memory serves). Either that book, or a review of it, pointed out a 22 year (?) cycle of sunspots appeared to correspond to the intermittent alignment cycle of Jupiter and Saturn alone. Thanks Little Bill.