Earthquake safe?

A magnitude 7.0 temblor is due along Wasatch Fault

Published: Sunday, Feb. 13 2005 12:00 a.m. MST

Paul Ernst, standing inside the dome, is project manager for the Capitol renovation project. Ninety-eight percent of Utah's tremors go unnoticed. But that could change.

August Miller, Deseret Morning News

OREM — Utah shook with 20 minor earthquakes last week, underscoring the alarm sounded again by Utah seismologists and geologists in the wake of December's tsunami that a major quake is due along the Wasatch Fault.

Those small tremors went unnoticed, just as 98 percent of the hundreds of Utah seismic events do each year.

But each Earth-shimmy is a reminder that much of Utah is at the mercy of faults that move slightly each day, drawing the region closer and closer to a major episode.

The state is due for a magnitude 7.0 quake in the next 50 to 100 years, say experts such as Brigham Young University professor Ron Harris, who chronicled the buildup of pressure finally released as a 9.0 earthquake that caused a tsunami and killed more than 200,000 people along the rim of the Indian Ocean.

The largest earthquakes in the state's documented history occurred in 1934 just north of the Great Salt Lake and in 1901 near Richfield. Those tremors measured 6.6 and 6.5, respectively.

Utahns are not ready for quakes even of that magnitude, Harris says. Buildings could collapse; water pipes could burst; freeway overpasses could crumble — and thousands could die.

"If it happened in the early morning hours, when most are still asleep . . ." Harris says, letting his sentence finish itself.

Because there has been little noticeable seismic activity in Utah's recent history, earthquake preparedness is not high on most Utahns' list of things to do.

But if what experts such as Harris are predicting happens, then within the next century, residents along the Wasatch Front will not only feel the Earth move but will become first-hand witnesses to the devastation an earthquake can unleash.

Consider waking in the morning to the radio crackling with news such as this . . .

A magnitude 7.5 earthquake, centered directly below downtown, hit Salt Lake City this morning shortly before dawn. Residents are sifting through thousands of older homes, which were not retrofitted to earthquake code, looking for survivors. The University of Utah's Marriott Library collapsed, trapping an estimated half dozen maintenance workers.

In Provo, 50 miles away from the quake's epicenter, thousands of BYU students living in off-campus apartments were killed while they slept. Many of the apartment buildings, built more than 30 years ago, collapsed because they were not upgraded to meet the state's seismic building codes.

Visibility is low along the Wasatch Front as smoke from fires caused by ruptured gas and electrical lines clouds the skies. Power lines are also down. The state's main thoroughfare, Interstate 15, is impassable from south of Provo to the Idaho border as many of the roadway's bridges and overpasses have collapsed.

The outlying communities of Ogden and the Cache Valley have sustained significant damage.

This scenario is a distinct possibility for Utah, given the pressure building along the fault lines spidering throughout the western branches of the Wasatch Fault, through downtown Salt Lake City and under the Great Salt Lake and Utah Lake.

Bob Carey, earthquake project manager for the Utah Division of Emergency Services, said the Federal Emergency Management Agency ranks Utah as a high-risk area for earthquakes because of the population's size and proximity to the Wasatch Fault.

Scientists have estimated that the Wasatch Fault has produced a large earthquake about every 400 years. Studies have concluded that the last large quake to hit the fault was as long as 600 years ago and as recently as 400 years ago.

Either figure illustrates that a large quake in Utah is overdue.

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