Nevada ranks third among the 50 states (behind California and Alaska) for the frequency of earthquakes.
Nevada is, geologically speaking, a fairly young territory. Nearly all the state’s mountain ranges, in fact, continue to grow—one earthquake at a time.
Las Vegas, specifically, is underlain by local fault lines. 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.
Some of the faults have the potential to produce strong earthquakes on rare occasions. 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. Of course, someday is highly variable, but to seismographers, "on rare occasions" means that the average time between the large earthquakes on any one of the faults is somewhere between 1,000 and 10,000 years.
Closer to the current calendar, the likelihood of an earthquake of that magnitude hitting Las Vegas is slim. Seismologists calculate a roughly 1 in 10 chance that a magnitude 6.0 earthquake — one large enough to cause significant damage — will strike the valley in the next 50 years.
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.
But it’s not just the fault lines under Las Vegas that could have an impact here. The worst shaking experienced the valley 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. 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 create havoc in Las Vegas.
Experts project that it could damage thousands of buildings, force tens of thousands of people into public shelters, kill in hundreds, and cause economic damage of up to $25 billion.
For an interesting graphic look at recent quakes around the valley, go to earthquaketrack.com/us-nv-las-vegas/recent. And for a map of the fault lines running through the valley, visit earthquakes.unlv.edu/map.
