The United States Geological Survey (USGS) has retracted an alert for a significant earthquake near Lake Tahoe, declaring the seismic event a complete false alarm. Millions of residents across Nevada and California were startled by the notification on Thursday morning, only to be told later it never happened.
Widespread Alert for a Non-Existent Quake
Just after 8 a.m. Pacific Time on Thursday 04 December 2025, automated systems broadcast an alert warning of a magnitude 5.9 earthquake. The reported epicentre was approximately 12 miles northeast of Carson City, the state capital of Nevada, near the Dayton area and the popular Lake Tahoe region.
The alert, sent to millions via the USGS's earthquake notification systems, prompted immediate concern. A quake of that strength, according to the Michigan Tech Earthquake Magnitude Scale, is typically powerful enough to cause strong shaking and slight damage to property.
Swift Retraction and Investigation Launched
Officials quickly realised the report was erroneous. The USGS removed all information about the supposed tremor from its website, leaving the public confused. A spokesperson for the agency later confirmed there was no such temblor in the region.
"The report was a bogus event," the USGS spokesperson stated, adding that the agency's automatic earthquake detection system had erroneously generated and disseminated the alert. The reason for the system's malfunction remains unclear, and an investigation is underway to determine what triggered the false positive.
Multiple law enforcement agencies in cities and counties surrounding the reported epicentre corroborated the USGS's findings, confirming they felt no ground shaking or witnessed any other signs of an earthquake.
Questions Over Seismic Monitoring Reliability
The incident has raised questions about the reliability of automated seismic alert systems, which are critical for public safety in earthquake-prone regions like California and Nevada. The USGS spokesperson emphasised that the agency is working to understand precisely what went wrong with its detection protocols.
While false alerts of this scale are rare, the event underscores the complex challenges in monitoring seismic activity in real-time. Residents who received the initial alert were left with a moment of unwarranted alarm, highlighting the fine balance between rapid warning and accuracy in emergency communications.
