In brief
A major earthquake alert sent by the United States Geological Survey (USGS) for a non-existent 5.9 magnitude quake near Carson City, Nevada, caused panic in California before being swiftly cancelled. The incident marks a significant failure in the USGS's earthquake detection system, with an investigation underway to determine the cause.
An alert sent on Thursday warning of a strong earthquake in northern Nevada was issued in error, according to the United States Geological Survey (USGS).
At 08:06 local time, the USGS reported that a magnitude 5.9 earthquake had struck near Carson City, the state capital. The alert reached people nearly 200 miles away in the San Francisco Bay Area, triggering automatic warnings advising residents to drop for cover.
However, the agency then cancelled the alert minutes later and removed the corresponding entry from its website.
There was no M5.9 earthquake near Carson City, NV, the USGS said on X.
The USGS said the alert originated from its automatic earthquake detection system, which had erroneously generated the report. It said it was believed to be the first time the agency has issued a completely false earthquake notification.
An investigation is under way to determine what caused the malfunction.
Multiple law enforcement agencies in cities and counties near the reported epicentre confirmed the absence of any ground movement.
A magnitude 5.9 earthquake is typically strong enough to cause noticeable shaking and slight property damage, according to the Michigan Tech Earthquake Magnitude Scale.
