I was catching up on some The Party Line reading this morning when I caught the links to two articles from the East Bay Express written in February 2005 about the possibility and aftermath of a massive quake in the Bay Area.
Remember the FEMA 2001 report that said that the three most likely disasters are a terrorist attack on NYC (check), and a hurricane on New Orleans (check) — and a massive quake on SF? Uh oh.
What trenching reveals is nevertheless alarming. For example, it has shown that the Hayward Fault has ruptured at intervals of roughly 175 years over the last two millennia — although the four most recent breaks were only about 130 years apart. The last quake on the Southern Hayward Fault, which until 1906 was considered the “great” San Francisco earthquake, was a 6.9 shaker in 1868 — 137 years ago. There hasn’t been a quake on the Hayward’s northern segment since the American Revolution.
Hayward is the fault local geologists are most concerned about. The forecasters have calculated a greater than one-in-four probability that a large quake will hit on either the northern or southern segment by 2032. “These two earthquakes are likely to produce the greatest amount of social disruption and economic loss of any earthquake in the United States, potentially in the world, because it’s such a densely urbanized corridor and it affects such a rich economic environment,” Lettis says.
