while the 22-year periodicity is widely criticized as not nearly so regular as was first thought, it would be surprising were Parkfield to re-break in just 4 years. To be honest, it is not clear there is a characteristic earthquake patch at Parkfield.

I'm still puzzling over a recent Custodio and Archuleta paper that claims the 1966 earthquake broke a different section of the San Andreas than the 2004 event - check the link.

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