Are Americans prepared for a catastrophic earthquake?

To follow is an excerpt from the CQ Researcher report called "Earthquake Threat" by By Thomas J. Billitteri, April 9, 2010.

Last October some 6.9 million people participated in a statewide “Great California Shake Out” drill aimed at helping residents and businesses prepare for a quake in one of the world's most seismically vulnerable regions. Another drill is set for this October, and organizers have high hopes that participation will grow.

Still, disaster-preparedness officials worry that too many Americans are complacent about seismic danger. “As a society we are not prepared,” says John Harrald, research professor at the Center for Technology, Security and Policy at Virginia Tech University and chair of the Disasters Roundtable at the National Academies of Science. “As we showed in Katrina” — the 2005 Gulf Coast hurricane and flood that devastated New Orleans — “part of what we're not prepared for is the very broad and deep impacts of such an event. Other than a few areas, it's not really on people's radar screens.”

That's even true in quake-prone California. In Los Angeles, nearly half of adults polled recently said they would not be prepared if an earthquake hit.Footnote 9 A 2006 survey by San Jose State University found that seven in 10 Californians expected a big quake to strike the state and affect them, but only 22 percent considered themselves well-prepared.Footnote 10 Another survey found that fewer than a fifth of households have structurally reinforced their homes or had them inspected for quake resistance. [Footnote 11]

Patterson, at the Memphis quake-research center, says Americans often ignore the possibility of a catastrophic temblor because it's simply too horrible — or, on the other hand, too remote — to contemplate. “Earthquakes can easily cause a sense of dread, almost like a nuclear accident,” he says. “People want to put it out of their mind” because the consequences of a big quake are poorly understood and such events can't be predicted.

But ignoring the threat doesn't minimize it. “The biggest issue is the existing building stock,” says seismologist Mary Lou Zoback, vice president for earthquake risk applications at California-based Risk Management Solutions. The age and style of construction of the area's structures are the biggest predictors of what the potential devastation will be like, she says.

In California, building codes are “very good” for structures put up after the early 1970s, when modern earthquake standards were adopted, Zoback says. But, she and other experts say, huge vulnerability remains.

In San Francisco, Zoback says, 84 percent of residential structures were built before 1970, and 50 percent predate 1930, when the very first seismic building codes were introduced.

What's more, many multifamily residential buildings in California are two- to-four-story wood-frame structures open on the first floor for parking. “The whole ground floor is pillars,” Zoback says. “When you shake the building sideways, it's not strong enough to hold up against the [sideways] shear force.” Most of the estimated 60 people who died in the 1994 Northridge quake near L.A. were in those kinds of buildings, she notes.

Many California buildings have been retrofitted to better withstand quakes, though cities such as San Francisco keep no systematic records of such work, Zoback says.

Pedro Silva, an associate professor of civil and environmental engineering at George Washington University, in Washington, D.C., says one retrofit technique is to put reinforcement “jackets” around key support columns, a job that in some buildings can be done quickly without forcing tenants to move.

But many older buildings remain vulnerable because it is difficult to retrofit them. “People are taking [retrofitting] seriously, but retrofitting one of these buildings would require moving people out of those buildings. It means if you are the owner of an apartment building, it's going to be very costly,” Silva says. Plus, he adds, if a building requires major damage to retrofit it, the owner may be better off bringing the structure down and rebuilding it.

Bridges can be somewhat easier to reinforce than many older buildings, Silva says, “plus there's a much stronger political drive to retrofit those structures.”

The magnitude 6.9 Loma Prieta earthquake, which hit the San Francisco Bay Area during a 1989 World Series game, damaged more than 80 bridges and caused more than 40 deaths in bridge-related collapses. [Footnote 12] In the 1994 Northridge quake, which disrupted travel on major freeways, six of 2,000 bridges in the region failed and four others were badly damaged, mainly because of failure in support columns built before 1971. [Footnote 13] Silva notes that after the Northridge quake, many people pushed to reinforce area bridges. “People were just tired of all the business disruptions for three to six months and said we're not going to take it anymore.”

Ghilarducci of Witt Associates says that despite robust planning efforts in the Midwest and other areas, “a lot more could be done” to mitigate the inevitable destruction from a big quake. More focus should be placed on “the low-hanging fruit,” he says: strengthening unreinforced buildings, hardening bridges and other infrastructure and developing plans for business continuity after a big temblor.

A key predictor of how regions may fare economically after a quake is how well they are insured against loss. Zoback says that while insurance covered 55 percent of economic losses from Hurricane Katrina, only 10 to 15 percent of losses from a catastrophic earthquake in California would be insured. Many Californians have shunned earthquake insurance because premiums have risen — in many cases sharply to reflect the damage risk from ground shaking — while coverage levels have declined and deductibles have shot up.

In a recent study, Zoback found huge variations around the country in both potential quake losses and levels of insurance. For example, a magnitude 7 quake along the full Hayward Fault in California would cause an estimated $160 billion in economic loss, including damage to private buildings and contents and business interruptions. The bill would run $200 billion if the Pacific Northwest were struck by a magnitude 9 quake like one that hit there in 1700.

If a magnitude 6.5 quake hit Manhattan, losses could total more than $1.5 trillion, according to Zoback's calculations. [Footnote 14] Manhattan sits atop a zone of ancient faults, including a small one running down Harlem's legendary 125th Street, according to Applegate. He calls a quake underneath New York City an example of a low-probability, high-consequence event.

Neither New Yorkers nor Californians are well-insured for quakes. In both places, less than 20 percent of the economic loss would be covered, Zoback found. Conversely, in the New Madrid zone, where losses from a magnitude 7.7 quake would run nearly $200 billion, according to Zoback's calculations, insurance would cover more than 70 percent of the loss because of a much higher penetration of earthquake insurance.

The Issues:
* Are Americans prepared for a catastrophic earthquake?
* Is a catastrophic earthquake likely in the United States?
* Should development occur along earthquake faults?

For more information see the CQ Researcher report "Earthquake Threat" [subscription required] or purchase the CQ Researcher PDF.

[11] “Study Reveals Californians Need to Increase Earthquake Preparedness Efforts,” California Emergency Management Agency, March 5, 2010,
[12] James D. Cooper, et al., “The Northridge Earthquake: Progress Made, Lessons Learned in Seismic-Resistant Bridge Design,” U.S. Department of Transportation, summer 1994,
[13] Ibid.
[14] Mary Lou Zoback, et al., “National Seismic Hazard and Risk-The Problem,” presented at ATC-SEI Conference, “Improving the Seismic Performance of Existing Buildings,” Dec. 9–11, 2009.