SALT LAKE CITY -- As Utahns watch gripping television coverage of the earthquake disaster in New Zealand, many wonder if the same thing could happen here. The answer: it may be worse, according to an expert on structural engineering.

Jerod Johnson of Reaveley Engineers & Associates said he sees buildings throughout the Salt Lake Valley that might not stand up to a quake like the one in Christchurch, New Zealand. And Utah can expect a significantly bigger one.

"The risk for collapse of those buildings is very high," Johnson said.

Part of the reason the New Zealand video hits home in Utah is that Christchurch doesn't seem all that different from Salt Lake. Television images do not show flattened mud-huts and shacks this time. They show big buildings with multiple stories, collapsed in a heap, some with dozens of occupants trapped in the rubble. There have been compelling scenes of people scrambling from the ruins of tall buildings or escaping from damaged structures by climbing down a dangling rope.

Johnson says it could be a preview of what Salt Lake is in for when a big quake hits.

"It is going to be a devastating event," Johnson said.

The primary problem, there and here, Johnson says, is a large inventory of older buildings made of brick and stone. Without modern reinforcement, such buildings often can't take the extreme shaking delivered by a big quake. It creates hazards, even if the building doesn't fully collapse.

"Parapets that fall off, steeples that come off of churches, piles of rubble out in the street," Johnson said. "(It) is exactly what we can expect for buildings that predate any kind of contemporary standard for design and construction."

In Salt Lake, Johnson's firm has reinforced and stabilized many high-visibility structures including the Wallace F. Bennett Federal Building, the Utah State Capitol, the old Hansen Planetarium, the Tabernacle on Temple Square and the University of Utah's Marriott Library.

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Some screamed from inside collapsed buildings. One woman used her mobile phone to call her children to say goodbye. Others tapped on the rubble to communicate with those on the outside.

But Johnson said a FEMA study currently in progress estimates there are at least 2,500 big masonry buildings in the Salt Lake Valley that remain unreinforced.

"That does not include homes," Johnson said. "There are many homes that are comprised of the same kind of materials."

He believes those older unreinforced buildings are sitting ducks for the next "big one," the kind of strong quake that scientists say can be expected to shake up the Wasatch Front on average once every 1300 years. The last "big one" was about 1300 years ago.

"It could be today, but it might be a hundred years from today," Johnson said. "We don't know exactly when."

When it comes, a Utah earthquake could be more powerful than the one in New Zealand.

"With the magnitude of event that we expect, the 7 to 7.3 magnitude quake, unreinforced masonry structures do not perform well," Johnson said. "The risk of collapse is extremely high."

Johnson believes if such a quake happens during business hours, it could kill thousands of people in schools, office buildings, stores and apartments.

He said people who live or work in big, older buildings "would be prudent" to ask building owners whether they've assessed the risk from a big quake and what they plan to do about it.

E-mail: hollenhorst@ksl.com

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