LV quake of similar strength possible, but not likely

Tuesday, Dec. 23, 2003 | 9:15 a.m.

After Monday's central California earthquake of magnitude 6.5, geologists living in Southern Nevada said that a comparable temblor could occur in the Las Vegas Valley, though it's not likely.

"Oh, yes, we definitely have that potential here," said Cathy Snelson, assistant professor of crustal geoscience at the University of Nevada, Las Vegas.

Nevada is the third most earthquake-prone state, behind California and Alaska.

So far eight fault lines have been detected throughout the Las Vegas basin, but not much is known about how far they extend or how much they may shake during a major earthquake.

However, the likelihood that such a damaging earthquake will occur is not high, because large quakes have not occurred in Southern Nevada for 7,000 to 10,000 years, Snelson said.

"We have no idea when the next one will happen," Snelson said.

Earth scientists have not explored Southern Nevada's fault lines until the past decade.

That was one reason Snelson and a team of earth scientists detonated more than 7,500 pounds of explosives placed throughout the valley in July in an effort to create seismic waves underground. The study looked at how local earthquake fault lines work and where they are located.

U.S. Geological Survey scientists said that Monday's quake ruptured along a 15-mile segment of the Oceanic Fault in San Luis Obispo County in California.

Monday's shock waves did not reach Southern Nevada. A Metro Police spokesman said no one called the department about the quake.

The reason Las Vegas residents didn't feel it is because of the mountain ranges between here and the quake's epicenter, Snelson said. The mountains absorbed the shock like a giant sponge.

"It's another wake-up call," said seismologist Jim O'Donnell, a member of the Nevada Earthquake Safety Council.

The Federal Emergency Management Agency tested about 100 Southern Nevada emergency workers in a drill under the scenario of a magnitude-5.8 temblor last summer. O'Donnell was a seismic consultant for the exercise.

In the exercise, the quake was simulated on the Frenchman fault, one of the major fault lines in the valley that runs through Sunrise Mountain into downtown Las Vegas.

"It (would do) as much damage as a 6.5 (magnitude) because the scenario placed it under downtown Las Vegas," O'Donnell said.

It has been estimated that a major quake could cause $11 billion in property damage and kill at least 50 to 100 people in Las Vegas.

Burt Slemmons, an geoscience professor emeritus retired in Las Vegas from the University of Nevada, Reno, said Monday's quake occurred on an active fault zone south of San Simeon.

Slemmons said that Southern Nevada had recorded a quake between a magnitude 2 and 3 within the past week, southwest of Las Vegas in the Spring Mountains. At that magnitude, the quake was not felt by anyone.