Californians Take Part In Earthquake Drill As Researchers Warn Of Large-Scale Temblors
October 17, 2013 1:26 p.m.
Pat Abbott, Professor Emeritus of Geology SDSU
Related Story: Californians Take Part In Earthquake Drill As Researchers Warn Of Large-Scale Temblors
MAUREEN CAVANAUGH: Some of you are more alert to the threat of wildfire than they are to earthquakes. It is probably a good idea that we are reminded by of earthquakes today, during the annual great California shakeout. An estimated 800,000 people in schools and businesses in San Diego took part in the drill this morning. With more on what kind of earthquakes we might expect in San Diego. And on recent reports of an earthquake early warning system. I would like to welcome Pat Abbott Professor Emeritus of Geology at SDSU. Pat, welcome to the program.
PAT ABBOT: Good to be here.
MAUREEN CAVANAUGH: What is the potential for earthquakes here in San Diego?
PAT ABBOTT: We have a very real potential and of course eathquakes pan out over geologic time scale rather than over human time scale. The Mission was built in 1769 and that is over 300 years ago. We haven't had a big earthquake. Stress is being lowered into the rocks and get released every few centuries. We could have one now or not for 100 years. We know what causes them and where the faults are, how big of earthquakes can get, almost everything except that one thing that everyone wants. When is it coming we cannot tell you.
MAUREEN CAVANAUGH: What would a major earthquake look like here in this region?
PAT ABBOTT: I would like to get that in two different ways to let's take the Rose Canyon Fault that works right through the city limits. Somewhat elusive metaphor if we visualize throwing a rock into a pond of water. Where it there's all kinds of chaos. Now that kind of energy, that short-period, High-frequency energy is very hard on short structures such as houses and chimneys. The other one that we prepare for and got the Great Shakeout going is the San Andreas Fault. Ninety miles to the east of us on the straight line distance. That is the segment of San Andreas that is moved the least amount of time. I hasn't moved since 1690. Middle section 1857, Northern section 1906, so in a probablistic sense we think that the might be the next big earthquake in California ñ no guarantee. It might be. That one, we had a good practice run for the three years ago on Easter and we had that Baja California earthquake at Laguna Solana. Is good for San Diegans to know that they can last for many seconds. Is a nice warm up for a preview of the new bigger one.
MAUREEN CAVANAUGH: Also showed us that even if it's centered will quite a distance from way from us it can still a give good shake.
PAT ABBOTT: Particularly these long rolling waves that would help those shake very vigorously tall structures tall buildings and bridges. Things of that sort. You mentioned that take earthquake warning systems coming up those are after an earthquake to start. This is not telling you in advance. So two earthquakes we were just talking about your give is Rose Canyon Fault here in town, there is no warning. The warning system is based on the fact that different seismic waves travel at different cities the best is waves are the possible ones. The slinky kind of movement. They are not particularly damaging. Using that Easter earthquake a couple years ago. The P waves come through this fast as we do not feel. It's quite some lame later before the wave causes damage to come in. That is what the warning system is about. For distant earthquakes. You can get seconds or tens of seconds of warning before those big rolling earthquakes.
MAUREEN CAVANAUGH: We know in San Francisco for instance that the Marina District is quite susceptible to because of the way that it is built and what is built on. Are there any areas in San Diego County that would be more vulnerable than others?
PAT ABBOTT: We talk about the Marina District, the beautiful district to right on the bay. A lot of that is water saturated loose sediment. Let's accentuate up there a lot of degree from a 1906 earthquake on the bay. The main point is that of this foundation with water in it. When does that take ways we felt lifting and rolling motion. See for a moment that the foundation is just water. The liquifaction is very hard on buildings. Where do we have the loose sands saturated with water, hotels on Mission Bay. Coming up in Mission Valley. San Diego River sediment there. Skyscrapers, large buildings on them. This would be the most prone areas to the liquifaction.
MAUREEN CAVANAUGH: This happens to be the 24th anniversary of the quake that killed 63 people up in the Bay area. Wondering have we taken precautions in California ñ in the state of California court so that we don't have casualties like that again?
PAT ABBOT: California does a great job with earthquakes. Wildfires, pathetic. Every time we have a major earthquake within the following your legislature may pass we try not to repeat the same mistakes. May I ask you give an example? Talk the earthquake killed 63 people that people. That Haiti earthquake in 2010 was almost a quarter of a million people. What is the difference between 63 and the quarter million people dead? Not the earthquake, but the buildings. We can look at what we are doing. That we're satisfied, but we're doing well in terms of adapting to earthquakes.
MAUREEN CAVANAUGH: One of the most recent times we've talked we had a conversation after an 8.8 earthquake in Peru. You said at the time California ñ I think some of California could never have an earthquake that severe? Why is that?
PAT ABBOTT: We're back to plate tectonics. Everyone knows that by now, but these are like pieces of eggshell 60 miles thick. They can do three things. They can pull apart from each other, run past each other, or collide. Our San Andreas Fault slides past. The bigearthquakes. The biggest earthquakes are with the two plates collide. One rides over the topof the other one. Significant but minor compared to Washington or Oregon.
MAUREEN CAVANAUGH: Is that also true for the that we hear there are new faults being found with more sensitive seismic equipment of the coast. Of the coast of California in general. Does that change the potential for powerful earthquakes?
PAT ABBOTT: We do find more faults all the time. These huge matches slide past each other it's almost like a bulldozer pushing things up there. Still basically smaller faults. The top out in the magnitude y. Where of course in Japan 9.0. They had a 9.0 in Washington on January 26 in the year 1700. They are in a different ballpark.
MAUREEN CAVANAUGH: You mentioned ñ and I mentioned to the opening phase early warning detection systems. Gov. Brown has signed a bill to get an early warning earthquake detection system in place by 2016. But are we talking about something that is only to give the sections of warning?
PAT ABBOT: That is correct. It's not tell you when an earthquake is going to occur, it we say once it has started week can be notified of the earthquake in progress. The more time you get its depending on how far away you are. This is the thing, Governor Brown has been a supporter. I see this the public ñ private thing. What can need something 1000 seismometers or more. That is big, millions of dollars. Once all the instruments are in place that you'll need to see private enterprise things. You should see an app that shows you when an earthquake is in process. If you desire.
MAUREEN CAVANAUGH: Is it worth that kind of expenditure? Considering the technology that we have now?
PAT ABBOT: Of course I'm biased being in that field as a disclaimer but I like it because we get more scientific information but there a lot of systems to the can benefit from that. The Japanese use it to automatically stop bullet trains in progress. So we don't have a derailment. Things like a hospital operating room you don't want to be surprised. It's like to go to get in on auto shutdown systems. There's a lot of ways society from benefit from and stay safe from these things. I'm afraid that I'm a biased a fan of that.
MAUREEN CAVANAUGH: Giving us a lot of good information on this. On the great California Sahkeout Day. I've been speaking with Pat Abbott Professor Emeritus of geology at San Diego State. Thank you.