Quake forecasts shaky

RENO -- There's no way to know whether recent earthquakes in northeast Nevada and near Reno are an indicator that a bigger quake is coming.

"We can say with 100 percent certainty that large earthquakes are going to happen in western Nevada. We can't say when," said John Anderson, director of the Nevada Seismological Laboratory.

In an average year, he said, Nevada has one earthquake of magnitude 5.3 or greater and a magnitude 6 about every four years, and a magnitude 7 about once every 30 years.

Earthquakes occur in Nevada because the state spreads out as it ages. That spreading, coupled with a constant grinding along the San Andreas fault as the Pacific Ocean floor tries to move northwest toward the Oregon coast, is why Nevada is the second most seismically active state in the lower 48 states, Anderson said.

A magnitude 6.0 earthquake Feb. 21 damaged much of old downtown Wells in Elko County. It was followed by a swarm of smaller earthquakes, including a 3.1 temblor Wednesday 5 miles west of Reno.

Anderson sees no cause for alarm, saying, "The bottom line is that it is not unusual. The swarm by Wells is a little more unusual than the swarm by Mogul."

Contrary to popular belief, little quakes do not release energy and prevent bigger ones, he said.

"Small earthquakes are a reminder that we live in an active area, but they're not useful for releasing the pent-up energy," Anderson said.

"When you look at all the energy released, 90 percent of the energy released is released in the big earthquake."