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Is Utah ready for a serious earthquake?

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Stunned world sees devastation in Turkey: city blocks of rubble, tilted buildings pancaked onto their lower floors, rescue workers desperately digging for survivors.

The 7.4 earthquake that struck on Aug. 17 killed at least 13,472 people, injured 27,164, left thousands missing and hundreds of thousands homeless.Through the filter of TV screens and grainy photographs in newspapers, with stricken Turks crying out in their own language, the earthquake -- centered near Izmit, Turkey -- seemed distant and somehow unreal. But could something that widespread and devastating happen in Salt Lake City? Yes and no.

Yes, an earthquake that large is plausible in Utah's greatest population center, since the Wasatch Fault -- one of the country's most dangerous fault lines -- underlies Salt Lake City. Much of the land in the western part of the valley is prone to liquefaction during a quake, which would cause buildings to tip over as if they were built in mud.

But no, the damage may not be quite as horrific because Turkey had shoddy, poorly enforced building codes where it had any at all.

Which isn't to say that Utahns should feel complacent. Big public buildings would not be as prone to fail here, but older brick homes -- and Salt Lake City has thousands of them -- are exceptionally weak, and most were built without reinforcement to protect against earthquake destruction.

According to a study published in 1996 in the Journal of Geophysical Research, the Wasatch Front faces a 30 percent probability of an earthquake of magnitude 7 or higher in the next 100 years. A report by the Utah Geological Survey, using newer information obtained by digging trenches in historic faults, is even more pessimistic: It estimates that Salt Lake City has a 57 percent probability of a magnitude 7 quake during the next century.

The University of Utah Seismograph Stations estimate that a 7.5 earthquake in the central section of the Wasatch Fault would damage buildings in Salt Lake, Davis, Utah and Weber counties to the sum of $4.5 billion. But because of the disruption in work, the injuries and many other effects, "this may only represent 20 percent of the total economic loss," adds a station publication.

Multiply it by five to get the total damage, and it comes out to a $22.5 billion price tag.

In 1976 the USGS found that a worst-case earthquake in the central Wasatch Fault would kill 2,300 -- assuming that local dams do not fail and send walls of water roaring down canyons. Meanwhile, 9,000 would be injured and 30,000 homeless.

"Unreinforced masonry buildings -- for example, brick homes built before 1960 -- are particularly vulnerable to ground shaking and are expected to account for 75 percent of the building losses," adds the seismograph stations' report. Meanwhile, electricity, natural gas, water and sewer lines would fail. Disruptions would hit highways, bridges, airports, railroads and communications systems.Requires Adobe Acrobat.

Over the past few decades, seismic safety has improved in building codes. But older structures are not required to retrofit if they are not remodeled.

"They're more or less grandfathered in," said Jim Bailey, a structural engineer who is one of about a dozen commissioners on the Utah Seismic Safety Commission.

"If it's built and nothing's being done with it, there's no requirement to do anything with the building to make it safer, unless it has an obvious on-going structural problem." For older buildings, remodeling or a change in use trigger the requirement to retrofit according to the Uniform Building Code.

Seismic codes were written into Utah's design requirements in the 1960s, but real enforcement didn't begin until around 1970. At that time, the state rating was changed from Seismic Zone 2, light earthquake danger, to 3, moderate danger. Only California and Alaska had a higher danger.

"A statistic I have heard is, 30 percent of the buildings presently -- including homes and commercial buildings -- would be considered unsafe in a Zone 3 type earthquake. That's because there's a large number of buildings that are unreinforced masonry, which is an extremely dangerous type of construction."

Bailey said such brick structures are "very vulnerable to collapse."

But Zone 3 may not be strong enough protection.

"There are a lot of people in the state, too, who believe that Salt Lake or portions of Utah should be Zone 4," Bailey added.

The Uniform Building Code in effect today is actually only a minimum designed to protect life. "The general public and (building) owners don't realize that what they're getting is a minimum thing," he said.

A building constructed to code may not collapse during an earthquake, but could be a complete financial loss nevertheless.

Soon the debate over which zone to apply may be moot. Utah may adopt a new system called the International Building Code 2000, in which building codes are based on proximity to active faults. "That will determine what force levels you have to design for," he said.

Also, a system known as performance-based design will allow the building's owner to specify what degree of protection he or she wants for a new structure. Everyone will have to build to a basic safety level designed to prevent the building's collapse, but then other levels of protection will be optional.

Whether the International Building Code 2000 goes into effect is uncertain. "It is really a major change," he said. "The cost of new construction will likely go up" if the code is adopted.

"It'll be the equivalent of having to design for at least Zone 4 if not higher, if this new code passes."

The code will most likely become widely available for study in the spring or summer of 2000. Then Utah officials will study it and decide around January 2001 whether they should change it or adopt it.

Bailey thinks the change would be a good thing, "but I'm still reserving my judgment until I've had time to really study it. Again, I don't want to see the economy strangled because of suddenly huge seismic requirements that may be in excess of what's really prudently needed."

Utah building rules require that if a building gets a new roof, and the building is of unreinforced masonry with parapets or other structures that could fall off in an earthquake, any parapets must be braced and the roof must be tied to the walls.

"As far as cost-benefit, it's great because so many people are killed from parapets falling off buildings in earthquakes," he said.

Does Utah have any requirement to make homeowners retrofit so that their houses are safer? No.

"That would be unfeasible, I think," he said. "You just can't condemn all older residential parts of Salt Lake . . . That just would not happen." If homeowners want to retrofit, they can obtain guidance from contractors or the Utah Geological Survey.

Schools are a different story.

About 10 years ago, the Salt Lake School District assessed the risks to its students from earthquakes and decided to retrofit buildings to a higher standard. Taking account of possible soil liquefaction, the buildings will be able to meet Zone 4 requirements when the program is finished in another 10 years.

First to be rebuilt where the three high schools. That rebuilding and the start of work on a couple of other schools cost $140 million.

In May, the school district's voters approved a $136 million bond, much of which will be used to accelerate the seismic upgrading.

"Three-fourths of all of the schools in the district will be completely rebuilt," said Gregg Smith, who serves the district both as engineer and as the director for buildings and grounds.

Besides the rebuilding and retrofitting, the district's structural engineers are helping to make the interiors safer. "Falling objects result in most injuries," Smith said. Certain kinds of hanging lighting will be eliminated.

Heavy tape will crisscross windows to prevent glass from flying during an earthquake. Heavy objects such as computers, tables and overhead storage areas will be secured.

"Parapet walls probably represent the biggest hazard we have. So we're going to take the moneys from Project Impact and go in and reinforce and tie back those parapet walls."

Project Impact is a national program sponsored by the Federal Emergency Management Agency, which has signed up 118 cities including Salt Lake City and Centerville. Private, local and state interests also are involved.

Around the time the school bond passed, Salt Lake City received a $300,000 grant under Project Impact. It's to be used to protect against flooding as well as for seismic safety. Of this, the school district gets $23,000 for the improvements Smith mentioned.

"We're trying to focus on everything we can within our buildings," he said.

Meanwhile, the most dangerous schools will be rebuilt first.

Of the district's 37 buildings, the three high schools have been rebuilt to meet the new stringent seismic safety standards. "Basically, it is nothing more than risk assessment," he said.

The three high schools were rebuilt first because they have more students, and thus a greater potential loss of life, than other schools. After they were upgraded, the district studied its other buildings and assessed the risk associated with each.

"The greater the risk, the sooner" they would be rebuilt. The last to be upgraded will be those with the lowest potential loss of life.

Steve Pratt, FEMA's earthquake manager for the six states of the region based in Denver, said he knows of no other school district going to as much effort as the Salt Lake District to make sure its children are safe from earthquakes.

"I'd like to think that as they complete this project, they're going to be the safest school district in the nation. I think that's where they're headed," Pratt said.

The school rebuilding program won't be completed for 10 years. What about today? If a major earthquake hits Salt Lake City this week, how badly will it damage the district's schools?

"Our brand new schools, we don't believe we'd suffer that much damage," Smith answered. But with the older buildings, he said, damage would be "considerable."