California residents have been listening to about “The Large One” for many years. The time period refers to a doubtlessly catastrophic earthquake that may strike one of many state’s main fault programs, significantly the San Andreas Fault and the San Jacinto Fault. Whereas scientists agree that one other main earthquake will occur sometime, they emphasize that they’ll’t predict the precise date, time or location.
Current research and seismic monitoring have renewed issues about California’s earthquake threat, particularly as stress continues to construct alongside a number of lively fault traces. Right here’s what specialists know concerning the state’s subsequent potential “Large One.”
When Was the Final ‘Large One’ Earthquake in California?
That is determined by how “The Large One” is outlined. For Southern California, specialists level to the 1994 Northridge earthquake, which registered a magnitude 6.7, killing 57 individuals whereas inflicting an estimated $20 billion in injury. Though it was devastating, Northridge was smaller than the catastrophic earthquake situations typically related to “The Large One.”
Others take into account the final true “Large One” because the 1906 San Francisco earthquake. The quake had a magnitude of seven.9 and ruptured a big part of the San Andreas Fault. The earthquake and fires destroyed elements of San Francisco and killed hundreds of individuals.
The opposite recorded “Large One” occurred in 1857, measuring at a 7.9 magnitude. It ruptured the southern part of the San Andreas Fault, between Parfield and Wrightwood, California.
Scientists are involved concerning the southern part of the San Andreas Fault to today.
When Will the Subsequent Large Earthquake Occur?
As for the following “Large One,” the brief reply is that no person is aware of when it would occur — but it surely’s imminent.
In response to the U.S. Geological Survey (USGS), earthquakes can’t at present be predicted with sufficient precision to find out the precise date, time or location when or the place the following main quake will happen.
Researchers have, nevertheless, developed fashions that estimate the chance of large-scale earthquakes in California. Earlier USGS forecasts found substantial chances for earthquakes of a magnitude 6.7 or increased over the following few years or many years.
However as of 2026, a current research discovered that elements of Southern California’s San Andreas and San Jacinto fault programs are at present experiencing among the highest stress ranges. A significant space of concern is the Cajon Move between the San Gabriel and San Bernardino mountains.
Sadly, as beforehand famous, scientists can assess the chance of possible quakes, however they’ll’t forecast the precise timing. So, the following “Large One” may occur tomorrow.
What Is the Highest Earthquake Magnitude?
There is no such thing as a theoretical higher restrict within the magnitude scale to measure earthquakes. The most important earthquake recorded in historical past was the 1960 Valdivia earthquake in Chile, which was measured at 9.5.
In comparison with that, the earthquake generally referred to as California’s “Large One” would possible fall within the magnitude 7.8 to eight.3 vary, relying on which fault ruptures and the way a lot of it breaks.
What Will Occur When California Will get the Subsequent ‘Large One’ Earthquake?
Scientists count on widespread shaking and infrastructure injury each time a significant San Andreas Fault earthquake happens.
Some of the extensively cited USGS situations, referred to as the ShakeOut State of affairs, fashions a hypothetical magnitude 7.8 earthquake on the southern San Andreas Fault. It tasks excessive shaking throughout Southern California, from Los Angeles to San Bernardino counties, and estimates round 1,800 deaths and $200 billion in damages.
Consultants urge residents to arrange emergency kits and contingency plans earlier than the following main earthquake strikes.