Nevada ranks third among the 50 states (behind California and Alaska) for the frequency of earthquakes. Still, there’s a big difference between the earthquakes of California and Nevada. In the former, experiencing earthquakes is almost commonplace. In the latter, earthquakes are recorded, but rarely directly experienced.
But don’t discount the dangers of earthquakes in southern Nevada. According to a 2003 seismic survey conducted by a UNLV geophysicist for the Department of Energy studying the Nevada Test Site and nuclear repository, Las Vegas will sustain a magnitude 6.5-7 earthquake someday.
Local fault lines underlie much of Las Vegas. Most of these define the borders of the valley where it edges up against the surrounding mountains, though some run under the city itself. In addition, larger tectonic faults, caused by the fluidity of the Earth’s crust, also undercut Las Vegas. These are the ones about which geophysicists and seismologists worry most. And the worries are real: In 2002, the Nevada Seismological Laboratory at UNR ranked Las Vegas the "seventh highest among metro areas in America outside of California" when it comes to the long-term economic damage that an earthquake would cause, based on 12-year-old census data. The 2003 report estimates that a 6.5-magnitude earthquake in Las Vegas, where buildings codes are much less stringent than in California, would incur $11 billion worth of damage.
About those building codes. Buildings in L.A. are designed to withstand seismic motion at a level of 10. The recent geophysical data on Las Vegas Valley indicate that the city could reach comparable levels. Yet the local codes apply to only half that much motion. Most injuries and deaths during earthquakes are caused by structures collapsing on people and dislodged objects striking people. "Building codes," according to a recent story in Las Vegas Weekly on the subject, "seek to at least ensure that, even if the house cracks and becomes uninhabitable during a quake, it doesn’t fall on us."
The last major earthquake experienced in southern Nevada occurred in 1992, registering 5.6 on the Richter Scale. It was centered at Little Skull Mountain near Yucca Mountain, and was felt in Las Vegas. The worst shaking experienced in Las Vegas reportedly occurred in 1857, when a massive earthquake was sustained by the San Andreas Fault. "Topping out at an estimated 8 on the Richter Scale," according to Las Vegas Life, "the quake caused a 225-mile-long rupture southeastward through Southern California, noticeably displaced landscape and river waters from Sacramento to San Bernardino, and moved the ground more than the 1906 San Francisco quake. An earthquake of that magnitude will inevitably be visited again upon the San Andreas Fault, and when it is, even though its epicenter could be hundreds of miles away, it could topple the older buildings in the Valley."
