A notification about a magnitude-5.9 earthquake in western Nevada Thursday morning was a false alert, the USGS said.
The quake alert generated by the ShakeAlert early warning system indicated an earthquake near Dayton, Nevada, about 20 miles northeast of Carson City, Nevada. The alert appeared on the USGS earthquakes map, but was deleted soon after.
“The ShakeAlert EEW system released an incorrect alert for a magnitude 5.9 earthquake near Reno and Carson City, Nevada,” the USGS said. “The event did not occur, and has been deleted from USGS websites and data feeds. The USGS is working to understand the cause of the false alert.”
False alerts can be triggered by several factors, the agency said.
For example, location algorithms sometimes misidentify reflected and refracted seismic waves created by one earthquake, which can turn into events far from the quake’s location. Noise in analog telephone circuits used to bring data from seismic sensors to computers also can be misidentified by automated systems as earthquakes. Software aimed at locating local quakes can sometimes mislocate a large earthquake on the other side of Earth, deep beneath the seismic network, the USGS noted.
“Adding to this complexity, there are multiple seismic monitoring networks that contribute their earthquake locations and magnitudes to the ANSS system,” the agency said on its web site. “These networks use different data and algorithms to locate the earthquakes, and sometimes the spatial separation of the contributed locations is so large that our systems interpret the independent solutions as distinct earthquakes of similar magnitude and location. In this situation, a delete message will be sent for one of the earthquake solutions but an earthquake did occur.”
NBCLA has reached out to the USGS for more details.
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