USGS ShakeAlert System Reportedly Generated False Earthquake Alert Affecting Nevada and California
On December 4, 2025, the USGS's automated ShakeAlert earthquake detection system erroneously issued a report claiming a magnitude 5.9 earthquake had struck near Dayton, Nevada. The reported false alert triggered emergency warnings on cell phones in parts of California, instructing residents to take protective action. USGS officials said no earthquake occurred and are investigating whether sensor noise or other anomalies caused the system failure.
- Date it happened
- 2025-12-04
- Organisation involved
- United States Geological Survey (USGS)
- Product, system or model
- ShakeAlert
This incident was imported from AI Incident Database and is used under CC BY-SA 4.0. Our additions to it — the structured fields, the translation, the checks against other reports — are published under the same licence.
This is a record of what was reported, not a finding that anyone broke the law. If it names your organisation and you believe it is wrong, the corrections process is free and open to everyone.