USGS: "The Shakeout Scenario" (S. Cal's Big One)

Just released this morning, an epic USGS disaster scenario on a 200-mile rupture of the San Andreas Fault in southern California. This is regarded as the most likely next "Big One" in southern California. The report looks very comprehensive and I plan on reading it in the next week.

Summary (including shake map)
http://pubs.usgs.gov/of/2008/1150/

The full report (over 300 pages)
http://pubs.usgs.gov/of/2008/1150/of2007-1150.pdf

Press Release
http://www.usgs.gov/newsroom/article.asp?ID=1947&from=rss_home

USGS also today issued new materials on the Bay Area's Hayward Fault.
www.usgs.gov

Our goal in the ShakeOut Scenario is to identify the physical, social and economic consequences of a major earthquake in southern California and in so doing, enable the users of our results to identify what they can change now—before the earthquake—to avoid catastrophic impact after the inevitable earthquake occurs. To do so, we had to determine the physical damages (casualties and losses) caused by the earthquake and the impact of those damages on the region’s social and economic systems. To do this, we needed to know about the earthquake ground shaking and fault rupture. So we first constructed an earthquake, taking all available earthquake research information, from trenching and exposed evidence of prehistoric earthquakes, to analysis of instrumental recordings of large earthquakes and the latest theory in earthquake source physics. We modeled a magnitude (M) 7.8 earthquake on the southern San Andreas Fault, a plausible event on the fault most likely to produce a major earthquake. This information was then fed forward into the rest of the ShakeOut Scenario.

The damage impacts of the scenario earthquake were estimated using both HAZUS-MH and expert opinion through 13 special studies and 6 expert panels, and fall into four categories: building damages, non-structural damages, damage to lifelines and infrastructure, and fire losses. The magnitude 7.8 ShakeOut earthquake is modeled to cause about 1800 deaths and $213 billion of economic losses. These numbers are as low as they are because of aggressive retrofitting programs that have increased the seismic resistance of buildings, highways and lifelines, and economic resiliency. These numbers are as large as they are because much more retrofitting could still be done.

Thanks for the post. Supposedly we'll have a big one here in Utah soon, so this should be beneficial for us too.

frightful indeed. I'm making my own shelterbox and hoping that I won't be near the epicenter.

Terrifying prospects indeed! Now to step up my level of preparedness even more.

As they say, "It's not a matter of if, it's a matter of when."

That report makes San Diego look fairly safe (relatively speaking). Damage here in that scenario's model was relatively light.

Since that's what they consider most likely, I'll back off and cease all preps No point in getting all ready if I live in the wrong place.

Maybe I should move to Riverside.

Having been thru a 6.4 shaker, my guess is that a monster like 7.8 will not be confined to those eight counties, it will really whack the whole state. Making South Dakota look better and better...

They suggest one of the biggest problems would be putting out all the fires after the quake. With water lines busted and the likelihood of it happening on a dry, hot, and windy day (about 7-8 months out of the year) things could go from bad to very, very, bad.

The Channel Islands will end up in the Pacific Ocean.

Uhmmmmmm . . . .


They already are.

Yeah, and a mere 7.8 magnitude earthquake on the southern San Andreas Fault won't put those islands anywhere else.

Where's Foghorn Leghorn when you need him? [It's a joke, son, a JOKE, doncha' get it?]

Jeff

Fires? Fires? Broken gas lines surrounded by a bunch of nervous smokers who desperately need to calm their nerves?

The whole reason the Channel Islands exist is to protect Santa Barbara from tsunamis.

Sue

Past earthquakes in that region haven't impacted as large an geographic area as one might expect from the energy involved. Perhaps the bedrock isn't solid enough, or the faults direct energy in other directions - I don't know.

The New Madrid zone is the one to worry about. Earthquakes are infrequent enough that building codes and inspections are not up to the job. The image on this page indicates what I'm talking about: look at the size of the affect area for a 6.8 quake! That area is full of tilt-up construction and it's likely to be a re-run of the Chinese disaster.

"...look at the size of the affect area for a 6.8 quake..."

Yup, and a 7.8 quake is A LOT bigger than a 6.8...