T1B

Risk of Big California Quake in Next 30 Years Rises

The risk of a major earthquake hitting California in the next 30 years has risen dramatically, scientists said Tuesday, using improved forecasting techniques.

Earthquakes are notoriously hard to predict and while seismic activity in California has stayed mild in the last century, experts expect a big one to strike some time in the future -- they just don't know when.

"The likelihood that California will experience a magnitude 8 or larger earthquake in the next 30 years has increased from about 4.7 percent... to about 7.0 percent," said the US Geological Survey.

A report, known as the Third Uniform California Earthquake rupture Forecast, acknowledges the complex nature of fault lines and uses new methods to account for future risk.

"The new likelihoods are due to the inclusion of possible multi-fault ruptures, where earthquakes are no longer confined to separate, individual faults, but can occasionally rupture multiple faults simultaneously," said lead author and USGS scientist Ned Field.

"This is a significant advancement in terms of representing a broader range of earthquakes throughout California's complex fault system."

While the risk of a big quake went up, that of a more moderate one actually declined since the last assessment in 2008.

"The estimated rate of earthquakes around magnitude 6.7, the size of the destructive 1994 Northridge earthquake, has gone down by about 30 percent. The expected frequency of such events statewide has dropped from an average of one per 4.8 years to about one per 6.3 years," said the report.

Tom Jordan, director of the Southern California Earthquake Center and a co-author of the study, added: "We know that tectonic forces are continually tightening the springs of the San Andreas fault system, making big quakes inevitable.

"The UCERF3 model provides our leaders and the public with improved information about what to expect so that we can better prepare."

For some reason I'm really just not much more worried about it than I was last week.

Left Seater wrote:

For some reason I'm really just not much more worried about it than I was last week.

Amazing how we get comfortable with certain risks in our areas.

See also Florida with hurricanes, mid west with tornadoes, etc.

Mikey wrote:The Northridge quake woke me up, but I was many miles from any damage.

Diego in Seattle wrote:

Mikey wrote:The Northridge quake woke me up, but I was many miles from any damage.

You mean you weren't next to the epicenter??

-Moving Fail

Mikey wrote:Don't get me wrong, I do take the risk seriously. And we are about as prepared as we can be (my wine racks are secured and near the floor).

But a change in the model that now puts the risk at 7.0% in 30 years instead of 4.7% doesn't mean that the actual risk has changed. The ongoing drought has me more concerned than the possibility of an earthquake.

A major earthquake *can* be a lot more destructive than a tornado or hurricane (more than Katrina?) but they also are a lot less frequent. I've lived in California (both the Bay Area and SoCal) for over 50 years and could probably count on two hands the number of times I've actually felt the ground shake. Never been located where there was any damage, though my mom's town home in Cupertino (actually just the contents) sustained some damage in the Loma Prieta quake (1989). The Northridge quake woke me up, but I was many miles from any damage.

Papa Willie wrote:

Moving Sale wrote:I was at the game during world series quake.

In all seriousness - that couldn't have been a very good feeling - especially trapped in the midst of thousands of panicky people...

Papa Willie wrote:

Moving Sale wrote:I was at the game during world series quake.

In all seriousness - that couldn't have been a very good feeling - especially trapped in the midst of thousands of panicky people...

Jsc810 wrote: Northridge was moderate? I get that it wasn't The Big One, but moderate?

The blind thrust earthquake had a moment magnitude (Mw) of 6.7, which produced ground acceleration that were the highest ever instrumentally recorded in an urban area in North America,[5] measuring 1.8g (16.7 m/s2)[6] with strong ground motion felt as far away as Las Vegas, Nevada, about 220 miles (360 km) from the epicenter. The peak ground velocity in this earthquake at the Rinaldi Receiving station was 183 cm/s[7] (4.09 mph or 6.59 km/h), the fastest peak ground velocity ever recorded. In addition, two 6.0 Mw aftershocks occurred, the first about one minute after the initial event and the second approximately 11 hours later, the strongest of several thousand aftershocks in all.[8] The death toll was 57, with more than 5,000 injured. In addition, earthquake-caused property damage was estimated to be more than $20 billion, making it one of the costliest natural disasters in U.S. history.[9]

Moving Sale wrote: I was in some slut's house in Simi Valley during Northridge quake.

Moving Sale wrote:I was at the game during world series quake.
I was in some slut's house in Simi Valley during Northridge quake.
And...
I was in Paso on way to "Brett farve dad died" raiders game during that quake.
Felt them all. Trippy shit.

Papa Willie wrote:

Diego in Seattle wrote:Meh. Nothing can be done to prevent them, so why worry about it?

Kinda like Glowball Warming, eh?

Jay in Phoenix wrote: He said the seats and stadium were "rolling or waving" and it was completely surreal. We continued to cover the event live for the rest of the day and evening and they produced some amazing video. I was in SF about ten years ago at the Troll stop for Luther, CM and company when we had a very modest quake Saturday night, not too long after the Cubs/Giants game. I had never experienced a quake before, and though it was not too big a deal, it was very strange. Hard to imagine living in an area prone to this sort of periodic event, and especially when the San Andreas finally does give it up for real.