Nevada risk of earthquakes pales to Japan

The largest earthquake that scientists expect to occur on faults in and around the Las Vegas Valley would be more than 1,000 times less powerful than Japan's catastrophic 9-magnitude earthquake, State Geologist Jon Price said Monday.

The strongest earthquake that could be expected to strike the valley -- a magnitude 7 -- or even a magnitude 6, such as the one that toppled bricks off old masonry buildings in Northern Nevada's rural community of Wells in 2008, could result in damage and economic setbacks of $7 billion or more, he said.

"We certainly have an earthquake hazard in the state of Nevada," Price said. "We can have a damaging earthquake anywhere in the state. The Wells earthquake demonstrated that clearly."

Nevada ranks third behind California and Alaska of the states with the most large earthquakes during the past 150 years. Studies by the Nevada Bureau of Mines and Geology show the earthquake hazard in Las Vegas is about the same as Wells, where a 6-magnitude quake struck Feb. 21, 2008.

Among the lessons learned is that residents should secure, relocate or remove dangerous items that can fall on people so that things such as "flat-screen TVs don't come flying off and hit somebody," Price said, referring to a special report the bureau published last week on the Wells earthquake.

"If you are inside a building during an earthquake, stay inside. If you are outside, get away from buildings," the report's summary says.

There are seven known faults that cross the Las Vegas Valley's floor and at least four outside of it that are capable of a substantial jolt. If a 6.6-magnitude quake struck on the Frenchman Mountain Fault, for example, there would be 200 to 800 fatalities and 3,000 to 11,000 people would need shelter.

In addition, there would be major damage to 30,000 buildings with a projected economic loss in the valley of between $4.4 billion and $17.7 billion, according to a computer model by the Nevada Bureau of Mines and Geology.

Price noted that not every building in the state is built to modern earthquake codes, particularly in rural Nevada where there are many made of brick and mortar without reinforced steel.

"We're doing our best to address the issue," he said. "We're trying to get assessments to get a handle on the magnitude of the problem over time. The idea is to either retrofit or have those buildings torn down and replaced by those built to modern building codes."

The earthquake that occurred Friday in Japan, which the U.S. Geological Survey upgraded Monday from magnitude 8.9 to 9.0, was the fifth strongest worldwide since 1900.

It was so powerful that it sped up Earth's rotation by 1.6 microseconds, according to calculations by NASA geophysicist Richard Gross. The Dec. 26, 2004 Indian Ocean quake off Indonesia's island of Sumatra -- which killed more than 162,000 in 11 countries -- was roughly the same magnitude but the shift in Earth's mass caused a 6.8 microsecond surge in the planet's rotation speed.

Nevada's geologists aren't predicting any changes in stresses and strains on earthquake faults in the state as a result of the Japan quake. Nevertheless, Price said, the quake affected Earth's rotation slightly and "every GPS (global positioning system) station throughout Nevada and all over the world saw the effects.

"Some of these big earthquakes in the past, they'll ring the bell of the globe all over Earth. It's not unreasonable that something that was about ready to go anyway that this could be the straw that break's the camel's back."

Magnitude is a measure of the strength of an earthquake, or the energy from strain that's released from it. Strain from movement of tectonic plates and large rock masses can build up along a fault until it slips or snaps like a pencil that someone bends at both ends until it breaks, releasing energy.

The Associated Press contributed to this report. Contact reporter Keith Rogers at krogers@reviewjournal.com or 702-383-0308.