Interview with Dr. Lucy Jones. Worth a read.
http://www.planningreport.com/2014/11/07/lucy-jones-advises-la-resiliency-and-big-one
In order to improve Los Angeles' earthquake preparedness, Mayor Eric Garcetti has brought in the US Geological Survey's world-renowned Dr. Lucy Jones as his Science Advisor for Seismic Safety, to create a resiliency report. In anticipation of this document's release, Jones spoke with TPR to describe its scope and purpose. She explained the particular risks facing the city during a natural disaster, from water to housing stock, with a focus on the economic repercussions of "The Big One."
Excerpts
You are quoted saying at a fall Red Cross Whole Community Resiliency panel: “Imagine America without Los Angeles…That really is a possibility.” What did you mean to convey?
I’m referring to economic viability. It’s not that we’re going to kill off everyone in LA.
Look around the world at previous, very big natural catastrophes. For example, San Francisco was the city of the West Coast before its 1906 earthquake. It had five times as many people as Los Angeles did before the earthquake. In the decade after 1906, the population of Los Angeles grew five fold as people abandoned San Francisco and came south. Now, Los Angeles is five times the size of San Francisco. In that case, a major financial hub became significantly less important. Obviously San Francisco rebounded, but it took them decades.
The city of New Orleans has lost substantially more money in lost GDP of the region since the hurricane than it lost in Hurricane Katrina itself. We see this over and over: Really big natural catastrophes can change the economy of a region.
People are resilient. They find ways to come back. But the disruption from the biggest events can permanently change an area. We’re looking at how to make Los Angeles a place where people still want to live and work.
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At the CityLab Conference in Los Angeles this fall—hosted by Bloomberg Philanthropies, the Aspen Institute, and The Atlantic—you shared that when the San Andreas earthquake happens in Southern California, we know where the electric systems, water systems, and gas lines that cross the fault will break. But that hasn’t gotten anybody to do anything about them. Could you elaborate?
It was probably an overstatement to say it hasn’t gotten anybody to do anything about that. Different groups have talked about it and are planning how to work together after the damage happens, but we haven’t actually made any of those changes.
When an earthquake happens, one side of a fault moves in respect to the other—a distance of a few feet in a moderate earthquake and many feet in a bigger one. We expect the San Andreas to move between 10 and 30 feet. If you have a pipeline crossing the fault and one side of it pulls 30 feet away from the other, it breaks.
Mountains surround Los Angeles. The San Andreas is along the edge of those mountains. To get through them, lifelines come through the passes together. We call those “lifeline corridors.” When the fault moves, all of those lifelines are going to be pulled 10 to 30 feet from the rest of the lifeline.
Our ShakeOut analysis at Cajon Pass concluded that we were going to have an explosion and crater. It would trigger wildfires, because two petroleum-product pipelines cross each other with a natural gas pipeline at the San Andreas. All three are going to break at the same location.
We know exactly where the pipelines cross the faults, how much the fault is going to be moving, and that none of these lifelines have been engineered to handle that offset so far. Therefore we know they are going to break.
You can engineer to prevent breaking. This was done for the first time with the Alaska pipeline. It crosses a major fault called the Denali, which is very similar to the San Andreas. The pipeline was engineered to handle up to 20 feet of offset on the fault. That earthquake happened in 2002. There was 18 feet of offset and the pipeline did not break.
We know we can do this. We just haven’t, because these lifelines coming into Los Angeles are as old as the rest of the city. They’ve been here for a long time.
That’s not under the purview of the Mayor of Los Angeles, because the fault does not run through the city. None of those locations fall within the mayor’s reach. But we’re part of the region and we are all going to be affected in an earthquake. So we’re trying to understand which ones could be retrofitted, which ones are at risk, and what the consequences are of those risks.
All of the electric generation in the Los Angeles basin is in natural-gas fired plants. We switched over to all natural gas because of our air quality issues—those are the cleanest. But the natural gas all comes across the fault in pipelines. that are in danger of being disrupted, which has a real effect on electricity for the city.
The other big concern is water. In Los Angeles, we get over 85 percent of our water from outside the region, all of which comes across the San Andreas Fault in four aqueducts. All of those are going to break in the earthquake. A recent analysis by engineers at the Department of Water and Power concluded it would take up to 18 months to repair the aqueducts broken in the earthquake. We don’t have that sort of water supply from the Los Angeles side of the fault. We’re looking at months to years with inadequate water supply after a big earthquake in LA.
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There are hundreds of possible faults in Southern California. That’s why we have the greatest concentration of earthquake risk. We’ve combined a lot of people with a lot of faults, which can lead to many buildings being destroyed.
Exactly what happens to the housing stock will depend very much on which earthquake we’re talking about. Northridge was not that large—it was only a 6.7. But it was particularly devastating because it was close to people. The strong shaking was on the northern edge of the City of Los Angeles, with moderately strong shaking in the city.
Say we now have a similar-sized earthquake. But instead of being at the edge of the city, it’s down in the main basin with the strong shaking in Downtown Los Angeles. That case has the potential to wipe out a significant percentage of the building stock.
The San Andreas fault is outside the densest urban development. It does run through cities like San Bernardino, Palmdale, and the Coachella Valley. The combination of a lot of people some ways away and some people right on top of the fault puts our estimate from that earthquake at 300,000 buildings damaged enough to lose at least 10 percent of their value. 1,500 would actually collapse.
That’s a pretty devastating picture. First, building codes aren’t retroactive. Whenever we figure out that a certain type of building does badly in an earthquake and change the building code to prevent its further development, that doesn’t get rid of the old buildings of that style (except in the one small location that actually had the really strong shaking in that particular earthquake.) We have tens of thousands of buildings in Los Angeles with known significant deficiencies, which are not allowed to be built anymore. They are still here, with those same problems, because we haven’t had strong shaking south of the Santa Monica Mountains since Los Angeles has been developed. The last strong earthquake in the area was in 1857 when there were only 4,000 inhabitants here.
Beyond that, our current building code does not try to protect the building. It solely tries to protect lives. We say philosophically, “If you choose to build a building that leads to big financial loss after an earthquake, that’s your financial choice to make. You just can’t kill people in the process.” We have said that the role of government is solely about protecting lives. If your building is a complete loss but didn’t kill anybody, we say it was a real success.
In looking at an isolated building, I get why that’s a reasonable stance for government. The problem occurs when you put large numbers of buildings together. Our standard is a 99 percent chance of not collapsing. That means we’re accepting the collapse of 1 percent of our code-compliant buildings.
Plus, many more of them would not be useable. For every collapse in previous earthquakes, we’ve had about 10 red tags (buildings so badly damaged you can’t allow anybody to be in them) and another 40 yellow tags (damaged enough that it’s dangerous and has to undergo repairs). 50 percent of our code-complaint buildings could potentially be yellow or red tagged in the worst earthquake.
How do you maintain an urban environment and keep a city going with so many buildings that can’t be occupied? The needs of society are different in an urban environment, with a lot of buildings together, than they would be for a building in isolation.
