Earthquake Institute Warns Of A Big One Hitting San Diego

March 9, 2020 at 10:18 AM PDT

Speaker 1: 00:00 Speaker 2: 00:44 Speaker 1: 00:46 Speaker 2: 00:56 Speaker 1: 01:43 Speaker 2: 01:47 Speaker 1: 02:51 Speaker 2: 02:54 Speaker 1: 03:21 Speaker 2: 03:26 Speaker 1: 03:44 Speaker 2: 03:52 Speaker 1: 05:55 Speaker 2: 05:59 Speaker 1: 06:09 Speaker 2: 06:19 Speaker 1: 07:16 Speaker 2: 07:22 Speaker 1: 07:54 Speaker 2: 08:04 Speaker 3: 08:13 As if Corona virus worries weren't enough to keep us up at night. News from a major earthquake conference in San Diego is sure to cause some bad dreams. A paper presented at the 2020 national earthquake conference finds the risks San Diego faces from a quake on the Rose Canyon fault are much greater than previously realized and since we've always thought our distance from the San Andreas fault makes San Diego safer from earthquakes, experts say we are not prepared for a major earthquake running right through downtown. Joining me is dr Jorge min, S. S he is lead author of the San Diego earthquake report as well as serving as a California seismic safety commissioner and welcome to the program. Thank you. Thank you for having me. For more than a generation, we've known that the Rose Canyon fault is active, but what do we know now that raises the level of concern about a quake along the fault? Well, the over the last thing, 15 years, there are more and more studies showing the level of activity of their fault. For many years the fault was considered to be inactive. So when they built much of the existing infrastructure in San Diego buildings, et cetera, eh, they were designed and built the, the fault was inactive. So now we are realizing that the fault is active and even more active that previously believed. So does why is raising a concern that we have to address these eh, hazard, particularly with the existing all infrastructure and building stock in the city. What does that mean? That the fault is more active than we thought? That doesn't mean that there are more and more studies indicating the degree of capability of producing earthquakes. For example, initially we were thinking that probably we are talking about in the range of magnitude six, 6.5, et cetera. But recent studies have shown that the Rose Canyon fault, if it ruptures along with a new port Inglewood fault all the way to Los Angeles, um, could be capable of producing a magnitude 7.5. So that's different story. Now, uh, we are including these a scenario when we design, for example, buildings, eh, under the current building code. Uh, but for the purpose of this scenario, for the study that we did, we did for a magnitude 6.9 that is more plausible for planning purposes, for awareness purposes. So this is the, the scenario Eric Cook that, that with elected, when was the last time there was a big earthquake on the Rose Canyon fault? It is believed that it was in 1862. So in 18, 1862, there was a man among the two maybe are around 6.5 or so, uh, that is believed that was caused by the Rose Canyon fault and once center close to eh, old town. Uh, we have to remember that in those years the population of the city was about maybe less than 1000. When do scientists expect another quake along the fault? We don't have a crystal ball to tell you that. Uh, fortunately we can not predict earthquakes. We know for sure given the activity of default that there will be 100% probability that there will be an earthquake. Unfortunately, we cannot tell you a wing. Now your report outlines really some devastating effects that a major Rose Canyon quake could have on San Diego. Tell us what might happen. We have seen is three things, three main effects of the earthquake. Number one, the surface manifest manifestation of the fault rupture. We have to remember that the Rose Canyon rungs offshore from let's say ocean side or the way to LA Jolla, the fault enters in LA Jolla England and then grows eh mountain Solidad runs parallel to [inaudible] and then hits through uh, downtown and then goes again offshore going parallel to the coastline all the way to the border. So we have the problem that they will be a surface manifestation of the F eh fault rupture up to maybe two meters of a horizontal offset that make between six and seven feet. So imagine the effect on the existing buildings effect, especially in the infrastructure, water pipelines, sewage, electricity, communication, all pipelines, et cetera. Another effect is a strong ground motions because they faulty running through heavily populated areas and we have many buildings around and especially the adult building. Where are some of the buildings, especially that are old, particularly built B, B for the 90s. Those are highly vulnerable. Okay. Seismic LA born, they're born a number three. Uh, we have very close the ocean. We have very close the river and when we have shallow groundwater table, we are talking about liquefaction. So liquefaction is when the soil becomes from um, solid state into almost liquid state and then buildings think tilled and are severely damaged and that could a compromise our airport, good compromise. The phone functionality of the airport, the functionality of the port and all the other critical facilities, especially military facilities in the San Diego Bay. Uh, w part of the reason for the potential of such major damage has to do with San Diego not being as prepared as California, as other large metropolitan cities. Eh, probably, probably, I mean we are in the process of raising awareness about this. Um, I think something very important, either the population should be aware. Sometimes I go to Balboa park and I, I ask people about the Rose Canyon fault. Well, when I ask about the sung, Andrea, for many people, I mean everybody knows the San Andreas fault, but when I ask about the Rose Canyon fault, not everybody knows it, the Rose Canyon fault. And if they know about the Rose Canyon fault, they don't know where is the path, where, where is it? Is it going? So I think that there is still much work to be done in terms of raising awareness, educating people about the hazard. Uh, and the idea here is to get the people prepared. If people are prepared, they are not to be scared. Uh, so that's why awareness and preparedness. Just one last question. Some of us felt some shaking from a quake last Friday night. That wasn't round Rose Canyon, right? Not the earthquake was originated in, in South of the border, uh, South of the Mexicali Valley. It was a magnitude 5.5, but it was a good, a good reminder for us because we have this national conference running from Wednesday to Friday. On Wednesday we unveiled this earthquake scenario on the Rose Canyon fall. Uh, how will be the impact in San Diego? And then they last day, Friday evening, we have the friendly reminder from mother nature. Mm. I've been speaking with dr Jorge min, S. S he's lead author of San Diego earthquake, a planning scenario. And thank you so much for speaking with us. Thank you for having me here. [inaudible].

By KPBS Public Media

A magnitude 6.9 on San Diego's Rose Canyon Fault could damage 100,000 homes, cause widespread road and bridge failures and make parts of Mission Bay sink about a foot, according to a newly released report.