About 500,000 detectable earthquakes occur each year worldwide. About 100,000 of those can be felt, and 100 cause damage.
From 1975-1995 there were only four states that did not have any earthquakes: Florida, Iowa, North Dakota and Wisconsin.
Earthquakes can strike any location at any time. The world's greatest earthquake belt, the "circum-Pacific seismic belt," is found along the rim of the Pacific Ocean, where about 81 percent of the world's largest earthquakes occur.
Cynthia Sewell
Boise State University seismologist Jim Zollweg was cursing technology Thursday morning.
Years ago he had replaced traditional seismic recording devices - paper drums with often-clogging ink needles - with a public computer and monitor setup in the lobby of BSU's science building.
But early Thursday, as folks around southern Idaho and northern Nevada felt a 6.0-magnitude earthquake, the monitor was dead.
Windows shattered and building facades and signs fell in Wells, Nev. - and even people in Boise could feel the rolling earth - but no one was seriously injured in the quake, which was recorded at 7:16 a.m. Boise time. It was felt across much of the West, from northern Idaho and Utah to Southern California, and more than a dozen aftershocks were reported, officials said.
The most serious damage was reported in Wells' largely unoccupied historic district.
The town of about 1,300 was closed to all but residents, the Nevada Highway Patrol said. Officials posted signs along nearby highways telling motorists to fill up on gasoline elsewhere.
Three injuries were reported, but they were "not very serious - a broken arm, some head lacerations, some difficulty breathing," said Elko County Sheriff's Sgt. Kevin McKinney.
Q: What is the risk of an earthquake in Boise area?
According to his estimates, Zollweg said every 800 years the Boise area is at risk of an earthquake in the 7.0-magnitude range that could cause "serious damage," which Zollweg defines as multi-million dollar losses, economic hits, structural damage and possible loss of life. But Boise would not be leveled, he said. The U.S. Geological Survey reports a risk less than Zollweg's estimates.
Boise was settled in the 1860s, and there hasn't been a large seismic event during the city's relatively short history, Zollweg said.
The biggest risk of damage comes from unreinforced masonry buildings, which could collapse during an earthquake, and other building construction that can't withstand seismic shaking.
Q: What about Lucky Peak dam?
Bob Berger, the dam safety program manager for the Army Corps of Engineers, said officials have emergency action plans and measuring tools in place to protect Lucky Peak Dam - and downriver residents - in the case of a natural disaster.
The dam is engineered to withstand both worst-case and basic earthquakes from different distances, Berger said.
"The dam is not going to fail," Berger said.
The Corps is conducting a seismic safety review to re-evaluate the original design assumptions for the dam, Berger said. Researchers look for active faults within southern Idaho and come up with potential earthquakes and evaluate the dam's design structure to survive each particular scenario.
The Corps has also created emergency flood maps and works with local emergency planners to create evacuation plans in the case of a disaster, he said.
Q: Is Ada County prepared for natural disasters like earthquakes?
The Ada City-County Emergency Management agency is responsible for disaster preparedness for Ada County and cities within the county. ACCEM plans for hazardous materials, wildfire, dam break, terrorism and flood disasters.
Q: Has Idaho had large earthquakes?
According to the U.S. Geologic Survey, the first recorded earthquake that caused damage in Idaho occurred on Nov. 9, 1884, apparently centered on northern Utah. Six shock waves were reported in Paris, in Southeast Idaho, causing considerable damage to houses there.
Idaho's largest earthquake occurred on Oct. 28, 1983. The Borah Peak earthquake measured a magnitude of 7.0, killed two people and caused $12.5 million damage in the Challis-Mackey area.
Officials recorded a magnitude 3.3 earthquake near Rathdrum on Sept. 22, 2003.
Idaho recorded at least 400 earthquakes magnitude 3.5 or greater from 1974 to 2003.
Q: Why can't scientists predict earthquakes?
The majority of earthquakes across the country, including the Wells temblor, are random and can occur at any place at any time, whether or not there is a fault line, Zollweg said.
Zollweg said scientists can study past seismic events from a region and attempt to detect patterns, but given the vast time periods of geologic history, it is virtually impossible to pinpoint exact locations and times.
Kathleen Kreller: 377-6418
The Associated Press contributed to this report.
