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.

The Wasatch Fault is the longest in Utah, stretching over 200 miles from Fayette to Malad City, Idaho. The fault is made up of 12 segments, each measuring some 20 miles in length. Two of these segments — the Brigham City segment and the Salt Lake segment — are more likely to cause a large temblor than other segments of the fault.

The odds rise to 57 percent of an earthquake rumbling within the next century along these two segments, according to the Utah Geological Survey.

Movement along any of the fault's segments will not preclude a quake's effects from reaching other regions. For instance, the 1985 Mexico City earthquake's epicenter was centered in the coastal mountains of the Michoacan province. Much of the damage and loss of life that resulted from that magnitude 8.1 quake occurred in Mexico City — 250 miles east of the epicenter.

Simply put, nobody along the Wasatch Front will escape the effects of a large quake along the Wasatch Fault. There are, however, regions in the state that are safer from earthquakes than others.

"Counties in eastern Utah, in or around the Uinta Basin, are seismically safer than most," said Barry Solomon, who works with the Utah Geological Survey's Geologic Hazards Program. "The most dangerous areas are along the Wasatch Front, from Sanpete to Cache counties."

Like an early warning system, seismologists and geologists around the state have urged Utah legislators and city and county governments to toughen building codes and spend money to reinforce older, at-risk buildings.

For example, officials at the University of Utah say the Marriott Library would collapse in a magnitude 5.0 earthquake. Fund-raisers are seeking donations and the Federal Emergency Management Agency has given the U. nearly $3 million for seismic improvements — but university officials have told state lawmakers they need more.

Meanwhile, Utah taxpayers are paying for seismic upgrades to the state Capitol, and The Church of Jesus Christ of Latter-day Saints is doing similar work on another of the state's icons, the Salt Lake

Tabernacle, home of the world-famous Mormon Tabernacle Choir.

Harris says owners of old apartment buildings and homes should also upgrade. He fears the worst for some of his students at BYU if a massive earthquake were to hit Provo at night or early morning hours.

"Most students live in apartments built 20, 30, 40 years ago," Harris said. "Those are death traps. An earthquake in Salt Lake City or Nephi would cause them to collapse."

Any home built in Provo before 1970 is not seismic-coded for an earthquake, according to the city's emergency hazard Web site.

If preparation is the only defense, what should the average person do?

In choosing where to live, Harris researched Utah County with earthquakes in mind and chose a home on a higher, well-drained stretch of land. He made sure the house was built with updated materials that met the seismic code.

Harris said most people who die in earthquakes are killed by objects falling on them.

"If you can avoid that, you should be fine," he said.

Experts also recommend keeping cash on hand, safely storing food and water, understanding how to turn off the main water, gas and power lines to a home, and planning with family members what to do during a quake.

Homeowners also are advised to organize a portable 72-hour emergency kit, bolt down or provide a strong support for appliances such as water heaters, take a first aid class and learn which places are the safest in the home.

Many homeowners are unaware that their homes are not covered for damage sustained in an earthquake. In Southern California, for instance, it took the 7.1 magnitude Northridge quake in 1994 to alert homeowners there that their homes did not have earthquake coverage.

While most insurance companies offer earthquake coverage, it is not widely marketed.

On average, a homeowner can expect to pay $200 to $300 a year for earthquake coverage.

"In Utah, it doesn't matter where you live when it comes to earthquake insurance premiums," said Ken Lance, a Farmers Insurance agent in Provo. "Whether you live along the Wasatch Front or out in the desert, earthquake coverage costs the same."

E-mail: kmartinez@desnews.com; twalch@desnews.com