The US Geological Survey (USGS) issued a false alarm for a 6.8 magnitude earthquake that took place in 1925, which had led to the death of 13 people. The USGS said its computers had "misinterpreted" data causing the alarm to be wrongly issued.
News organisations across the US received the emailed alert about the quake which, if it had been real, would have been one of the largest ever recorded in California.
The USGS said that the work it was doing to revise and update information about where the historic quake struck had caused computer systems to misinterpret the data and think it was seeing a novel event, BBC News reported.
The agency also apologised for causing any alarm and said it was "working to resolve the issue". The 1925 quake is classed as a level seven-to-nine event on the intensity scale used by the USGS to measure the damage done by earthquakes.