This is a heads-up for Southern California Kossacks and those with friends and family there.
Shake Out is a giant earthquake drill to be held Thursday, November 13 in the Los Angeles area. It assumes a M7.8 rupture in the San Andreas fault and provides a scenario of the consequences. If you are not in the area the website is nonetheless a useful resource. The southern San Andreas fault usually has a Major Event every 150 years on average (the variability is large, however), but hasn't had one in 300 years. What happens if a Big One strikes the area?
You may think you know earthquakes (I've been through my share). Then again, after Andrew, Fran, and a dozen+ major storms Southeasterners thought they knew hurricanes. Then Katrina struck.
Here's the San Andreas fault.
If you fly along the coast, look out the window: it's a really obvious feature and you can't miss it. If you're driving and paying attention it's also an obvious feature. Note that the southern San Andreas has not had a major earthquake in over 300 years.
The shakeout scenario has a M7.8 earthquake originating at the very southern end of the fault near the Salton Sea. Justification for both the strength and the location maybe found here (warning: 312 pp PDF. All figures are taken from this reference). In this scenario the Coachella Valley is ground zero and will see very heavy ground motion; the rupture then propagates up the fault past San Bernardino and the Santa Clarita Valley sending shock waves as far as the Pacific Ocean to the southwest and beyond Bakersfield to the north. In this scenario San Diego is largely spared. The scenario is intended to be "realistic", not necessarily worst-case.
We have no skill to speak of at earthquake prediction (which fact should be kept in mind) but we do know that the San Andreas fault is an active one. We have a pretty good idea of its history, and we also know that strain has been building up in the southern part of the fault, where the fault is "locked" (that is, unlike the more mobile central section -- marked "creeping segment" above -- which has more frequent smaller quakes, this section requires a lot of stress before it lets go).
Here's a video of the scenario (available from the website). The clock in the lower left corner is a timer in seconds -- it only takes 1 minute from initial rupture for the quake to hit Los Angeles.
A few things to note:
- Because of the local geology the shock wave will "ring" and take some time to damp out in the Los Angeles basin and in the Oxnard/Ventura area (sorry, forget the name of the area). A typical large earthquake will last several seconds, flatten a few buildings, take out a few overpasses. The M6.7 Northridge quake lasted about 10 seconds and did this. In the Shake Out scenario, much larger amplitude motion than we saw in Northridge may last up to a minute in east Los Angeles and Ventura county.
- Los Angeles will be largely cut off except by air and sea. Roads and railroads to the east all cross the fault and the expected slip will render them unusable. Roads and railroads to San Diego and Santa Barbara will almost certainly be unusable in the damage areas. Water will be cut off, and running water may not be available for up to 6 months in the hardest hit areas. Here's how water gets to LA:
Communications will be mostly cut off, land lines as well as cell and internet (the major fiber optic trunk lines cross the fault). Same for natural gas. Same for supplies such as gasoline, groceries, ice. There may be some electricity back to some areas within about 3 days.
- Emergency crews will probably not be able to reach the hardest hit areas for days, perhaps a week or more. Cities as far away as Bakersfield and Santa Barbara will be hit hard and will likely be unusable as staging areas (but San Diego would work -- in this scenario). Hospitals still standing will be overloaded. Have emergency water, food to last that long, also first aid, medication, hand operated flashlights and radios. sarahnity has an excellent diary on disaster preparedness that's worth paying attention to (SoCal residents should tailor that to local needs. Tools like a crowbar and work gloves might be handy as well.) You will have to be the first responders, and neighbor will have to help neighbor, so learn about emergency procedures before you need to use them.
- Fire is expected to be a serious problem, especially with gas lines broken and with water cut off. There are many high density areas with wood-frame buildings.
- Unlike Katrina you will not have early warning. You'll have even less time than those hit by the 2004 Indian Ocean tsunami.
- We have no skill to speak of in predicting earthquakes, and it may well be another 300 years before this part of the fault goes in a big way. Or the fault may go next month. The San Andreas is not the only major fault in the region and some other fault may go, or it may go in a completely different way (eg, Santa Barbara is spared and San Diego gets hit hard), so don't put too much faith in the specific details of the scenario. But you do need to be aware of what you're potentially up against and do what you can to prepare.
Don't mean to be a downer but forewarned is fore-armed.