4.8 magnitude earthquake rattles Las Vegas, Nevada – scientists worry quake may be a precursor to a bigger event

May 2015 – LAS VEGAS, NV – After an earthquake prompted the closure of several flyover ramps in Las Vegas’ Spaghetti Bowl interchange on Friday, transportation engineers said the bridges remain safe for travel. The magnitude-4.8 earthquake happened at 11:47 a.m., and was centered in Caliente, NV, about 150 miles north of Las Vegas. The earthquake was later downgraded from a 5.3 to a 4.8 magnitude earthquake by the USGS. Immediately after the temblor, emergency crews shut down the ramps from U.S. Highway 95 southbound to both directions of Interstate 15. The Martin Luther King Jr. Boulevard ramp to I-15 southbound was also closed. This allowed crews to inspect a gap that appeared in the 95 ramp to I-15 southbound after the quake.

According to Mary Martini, District I engineer for the Nevada Department of Transportation, the gap existed before Friday’s earthquake, but the tremor shook loose a protective rubber casing that was covering the seam of the bridge, making the damage appear worse than it really was. “We’re issuing an emergency contract to repair the seam,” Martini said. “Meanwhile, the ramps remain structurally sound and safe for travel.” The ramps, which Martini said are made of cast-in-place concrete and steel reinforcements, reopened just after 4 p.m. They will remain open through Memorial Day, Martini said.

Several FOX5 viewers called the newsroom and posted on social media about the quake, saying they felt buildings sway and houses shake. One person said they heard a building creaking during the tremor. Officials said no injuries or other significant damage was reported. Graham Kent, director of the Nevada Seismological Laboratory, said Southern Nevadans shouldn’t be shocked by Friday’s earthquake. “At one level, it’s always a surprise when we get an earthquake, but this area carries enough tectonic strain, as they call it, or motion where these types of earthquakes or larger ones would not be unexpected,” Kent said. Nevada is the third-most seismically active state. Nearly 20 percent of the earthquakes in the United States occur in Nevada, but most are small and centered in remote areas. –Fox5 Vegas

Big quake overdue for Las Vegas: Researchers say there is better than a 50 percent chance of an earthquake measuring 5.0 or greater in the Las Vegas area in the next 25 years. Nevada is the third most seismically active state in the country. “People always need to be concerned about an earthquake because earthquakes always happen,” said UNLV geology professor Dr. Wanda Taylor. “They’re constantly happening.” At UNLV they study earthquakes worldwide and monitor the faults in our area. There are seven faults in the Las Vegas valley. The Frenchman Fault is the largest.

“Our current research indicates that our current faults in our valley are a greater problem than has been recognized,” Taylor said. In a valley like ours, the seismic waves can bounce back and forth, and with soft sediments, the damage can be extensive. “Our valley is bedrock with a bunch of softer materials so it’s kind of like a bowl of Jell-O,” Taylor said. The U.S. Geological Survey also predicts an earthquake on one of the big faults in Death Valley would shake Las Vegas the most. Two years ago, FOX5 traveled to Cal Tech in Pasadena, the world’s foremost earthquake think tank. Researchers say Southern Nevadans should be prepared. “The earthquake I’d worry more about in a city like Las Vegas is the big earthquake like a Northridge, 6.7, 7 or bigger,” said Dr. Susan Hough of the USGS. “Those earthquakes can happen.”

If a 6.6 earthquake hit Las Vegas there could be upwards of $17 billion in economic loss, approximately 30,000 buildings in the valley would be damaged, as many as 11,000 would need public shelter and up to 800 people could die. Some experts say it’s not a matter of if, but when. –Fox 5 Vegas  (Filed September 11, 2011)