Series of small East Bay quakes signals rising stress on faults

[Auggie]

From the San Francisco Chronicle, 5-6-15

SNIP

Although seismic activity on a small scale known as fault creep sometimes may relieve some stress that accumulates along a major fault, this week’s flurry would do nothing to reduce stress on the Concord-Green Valley Fault, (USGS Geologist David) Schwartz said.

There is a 3 percent chance that a major earthquake with a magnitude of 6.7 or greater could strike on the fault within the next 21 years, according to the most recent official estimate of quake probabilities in California, Schwartz said. While the odds of a really big quake hitting on that fault may seem small, he said, “the danger is always there.”

By comparison, the overall probability of quakes larger than 6.7 striking anywhere in the Bay Area during the same 21-year period is 63 percent, and it’s 21 percent for a major quake on the Bay Area’s segment of the San Andreas Fault, according to the estimate. A consortium of foremost earthquake scientists regularly estimates the probability of major quakes striking in California, and their work is released by the USGS.

“All the faults in the Bay Area are part of the larger San Andreas system, and they all indicate that the stress level of the entire system is rising,” Schwartz said.

FULL ARTICLE AT LINK: http://www.sfgate.com/science/article/Series-of-small-East-Bay-quakes-signals-rising-6247034.php

BOTTOM LINE: These earth movements in Concord originated at shallow depths about 4 to 6 miles deep. So any stress along the Concord-Green Vally fault is NOT LIKELY to be reduced, but rather increased.

It's that last paparagraph, about the entire San Andreas system, that is the eye-opener. Maybe I'm being alarmist about this, but I think it's a good idea to stock-up on some bottled water, canned goods and batteries, and keep the gas tank topped-off.

[Stargazer09]

1. To be honest

Regardless of the predictions, having emergency supplies on hand is always a good idea, especially in earthquake country. I don't think you are being an alarmist at all.

Geologists are always finding new faults and gleaning new information about existing ones. People who think that they are relatively safe may suddenly discover that the scientists missed something. It's better to be prepared for the worst.

[Auggie]

2. Yes, but does one prepare for a few days or a few weeks?

As I've posted before, don't underestimate the destructive force of even a 6.0 if it happens under your very feet (my experience last year). An 8.0 off the coast of San Francisco or under Oakland is going to cause weeks if not months of turmoil.

[Stargazer09]

3. I'd say be prepared for two weeks.

If you discover, after the disaster, that what you have isn't going to be enough, you'll at least have provisions for a trip out of the disaster zone.

I'm planning a move to western Oregon, and I know enough about Cascadia to know that I'll need to have about a month's supply of food and water on hand. That's going to be an ugly situation, when it happens.