Study: Vegas ground less stable, could make quakes more damaging

LAS VEGAS - The ground in the Las Vegas valley is less stable than previously thought and more prone to shaking in the event of a powerful earthquake, according to a two-year study of seismic activity in Southern Nevada.

A team of researchers from UNLV, the University of Nevada, Reno, and Lawrence Livermore National Laboratory in California studied eight known faults in the valley and found that a major earthquake could cause significant damage, the Las Vegas Sun reported Friday.

One fault one runs directly under the southern edge of the Las Vegas Strip, said Jim O'Donnell, a geophysicist and a member of the Nevada Earthquake Safety Council, which monitored the study data.

"There will be a lot of shaking going on on the Strip if the focal point of the earthquake is near those faults running under it," he said. "We're not in a high seismic area, but we're are at high risk for damage. We have the potential for magnitude 6 or 7 earthquake that could look like a 7 or 8."

The study was the first major review of the area's faults in more than a decade.

Cathy Snelson, a UNLV seismologist who participated in the study, said that while Nevada is among the most seismically active states in the nation, the area doesn't see many earthquakes.

The last noticeable quake was a magnitude-3.5 earthquake in 2001. Though relatively small, it was felt across the valley.

In August 2003, Snelson and several of her colleagues set off a series of underground explosions designed to mimic seismic activity.

After several months analyzing the data, Snelson's group determined that the types of rocks in some parts of the valley are less stable and would be more prone to shaking in an earthquake, adding to the potential for damage.

"Basins (like the Las Vegas valley) shake by factors of 10 when an earthquake passes through them," O'Donnell said. "A magnitude-5 earthquake elsewhere would be like a 6 here."

A 2001 estimate using software from the Federal Emergency Management Agency revealed that a magnitude-6.9 earthquake in the Las Vegas area could cause $11 billion in economic losses and thousands of deaths.