NEVADA — A magnitude 5.2 earthquake struck about 40 miles east of Reno at 1:17 a.m. Friday. The temblor followed a magnitude 5.7 earthquake on April 13 that occurred about 45 miles east of Reno and caused moderate-to-strong shaking in the town of Silver Springs, knocking items off shelves and out of cupboards. No injuries or damage were reported from the April 13 quake.

Two days before the magnitude 5.2 earthquake, a magnitude 4.4 earthquake occurred about 60 miles north of Las Vegas, with some people reporting weak shaking. Silver Springs is built on an old lake bed that amplifies shaking during earthquakes and contains many mobile homes, according to Christie Rowe, director of the Nevada Seismological Laboratory.

"I've been getting a lot of calls from residents of Silver Springs who are feeling the aftershocks — even down to magnitude 3. So they've been speaking about what seems like continuous shaking when they're having repeated aftershocks right after the main shock," Rowe said.

Many fault systems cross the California-Nevada border, including under Lake Tahoe, according to Rowe. Incline Village closed a school after discovering it sits on the Incline fault, which generated a magnitude 7 earthquake in geologic history. The Death Valley fault system is about 95 miles west of Las Vegas and has generated magnitude 7 earthquakes. The Hurricane fault system is about 75 miles from Las Vegas, located in the northern corner of Arizona and extending into Utah, and has been relatively quiet recently. There are also faults in Las Vegas itself, though little is known about them.

A hypothetical magnitude 7 earthquake near Las Vegas could cause about $21 billion in damage to buildings and infrastructure, according to the Nevada Bureau of Mines and Geology.

The U.S. Geological Survey runs an earthquake early warning system that sends alerts to smartphones or computers before shaking starts. The system operates in California, Oregon and Washington but not in Nevada. Congress has allocated money to the USGS to implement the system in Nevada, but additional funds are needed for full implementation. Budget cuts and hiring freezes at the agency have impeded expansion efforts, according to Rowe.

"How can you expand a program to a bigger area when the agency that runs it is short of staff?" she said. "Ironically, if we had a Las Vegas-area earthquake, the Californians who would be affected by that would get warnings. But in Nevada, we would not be sent the warnings."