'This Was a Warning'

Does this quake give us any clues about future southern California quakes in terms of when or where?
We tell people it's a very low probability that an earthquake like this might be a foreshock, but I think the more responsible way of looking at it is that this quake is a reminder. The L.A. Basin is fraught with potential hazards, the thrusting event as well as the large strike event, and we've been lucky. The San Andreas Fault on average ruptures every 150 to 200 years over the last several thousand years, and it has not ruptured for about 340 years. So every morning we wake up we set a new record between large ruptures.

Would you say Los Angeles dodged a bullet with this event?
Yes, thrust faults than can be a seven-ish event, this one got up to 5.4. But the point is they are there and people need to be prepared. The way I look at events like this, other than making our afternoon crazy, is that this is really just a strong reminder to people that earthquakes can and will occur in this region that are 100 times larger in energy; some day the big one will in fact occur. These are reminders to people to be prepared with food and water. Have your wall units bolted. Do your kids know where to go? People throughout southern California should have all of this already planned. Unfortunately, people don't ask us about this stuff when we don't have an earthquake, so during times like these we use you [the media] to answer the public's questions and remind them that we need to be prepared.

Can any of the things people do, from construction to detonation (or blasting), influence earthquake behavior?
Not really. In general, earthquakes will happen on their own erratic time calendar. But again, it's been a long time since we've had a large one. That's why the Dare to Prepare program is so important. It's a program whose motto is Shift Happens. They have a Web site: www.daretoprepare.org.

What are some of the things we'll be seeing from this program?
We'll be running both northern and southern California earthquake scenarios to see how well we are really prepared.  In southern California we'll create a San Andreas rupture scenario, and in northern California we'll have a Lake Tahoe large-earthquake scenario, with a tsunami.

Is a tsunami actually possible in Lake Tahoe as a result of an earthquake?
Yes, it is. In November we will assess where we are in terms of preparation. The universities, USGS, emergency services, the State of California, a lot of people and organizations will be involved in this because when the big one does hit, we won't be talking about a 5.4. It will be something like a 7.8.

Wasn't that the size of the San Francisco quake in 1906?
Yes, and that's what San Andreas can get to. San Jacinto is midrange seven, Elsinore is up to seven, then there are the possibilities of another big thrust earthquake in L.A., and they can get up to the sevens, as well. The whole idea behind Dare to Prepare is to get everyone in southern as well as northern California to realize that the big one is going to happen. This earthquake was a warning. If it increases awareness and preparedness, those are good things.

© 2008