6.0 Salt Lake.-area quake would take moderate toll

If a 6.0 earthquake — similar to what struck rural Nevada Thursday — ever directly hits the populous Wasatch Front, state officials predict it will kill some people, collapse older brick buildings, break water and sewer lines, knock out power and create widespread damage from falling walls, chimneys and items from shelves.

Still, that damage is only considered moderate. A bigger 7.0 or so quake — which experts have said has about a 1 in 5 chance of hitting the Wasatch Front in the next 50 years — could kill up to 6,200 Utahns, injure 90,000 more, at least moderately damage 42 percent of all local buildings and cause $40 billion in economic losses.

"It all depends on when an earthquake hits and where, and the size," said Bob Carey, the earthquake preparedness director for the Utah Division of Homeland Security, who has performed computer modeling of likely damage from different sizes of quakes here.

Carey said a 6.0 in Salt Lake County would likely cause "some loss of life, but it would be minimal" depending on the time of day it hit. "If it happens at night when people are home and asleep, it would be less of a problem" than if people are at work or school.

He said a 6.0 would cause major damage to "unreinforced masonry" buildings, built of bricks and mortar and no reinforcing steel. "Those buildings would take a pretty good hit," and many might collapse, he said. Of note, some schools are made of that type of construction.

"It's a recognized problem, but it's also a funding issue. You can only go as fast (to upgrade schools) as funding allows you to," Carey said.

Of note, just an hour or so after the Nevada quake hit on Thursday, the Utah Legislature's House Government Operations Committee endorsed a bill to require schools to conduct seismic evaluations of their buildings that could lead to fixing the most needy buildings first.

Carey said most structural collapses and serious damage would occur relatively near the epicenter of a 6.0 quake. But "non-structural" damage could occur far from it.

For example, Carey said, "With some of the older buildings downtown, I would expect to see their decorative cornices have problems. You may see some failure there. You will definitely see parapet damage from this. With that parapet damage, you always see partial wall failure."

A parapet is a low wall along the edge of a roof or balcony.

He adds that damage may be seen on higher floors of buildings because swaying is more severe there.