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1 month ago
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An earthquake swarm has broken out in Northern California and experts fear it's almost certain the region will suffer a major disaster by 2043.
The US Geological Survey (USGS) recorded dozens of small earthquakes in a region known as The Geysers, less than 75miles north of San Francisco.
The latest swarm included a 4.2 magnitude earthquake that struck near the city of Cloverdale just after 3am ET Thursday morning.
According to nearly 200 residents reporting to USGS, the noticeable tremor was felt as far away as the San Francisco Bay and the city of Palo Alto, over 100 miles from the quake's epicenter.
There have not been any reports of injuries or property damage at this time, and most of the reports to USGS described the quake as producing only 'light' shaking in the area.
Since the magnitude 4.2 earthquake, another 12 minor tremors have been recorded around The Geysers, a large geothermal field which lies atop a network of seismic faults, including the Bartlett Springs Fault Zone and the Healdsburg–Maacama Fault system.
The seismic outbreak has renewed fears that a major earthquake is not only possible in Northern California and the Bay Area, but is nearly guaranteed to erupt within the next 20 years.
According to a 2015 report by USGS scientists, there is a 95 percent probability that at least one major quake, stronger than magnitude 6.7, will strike somewhere in the region by 2043.
Dozens of small earthquakes, including a magnitude 4.2 quake, have struck Northern California Thursday morning (Stock Image)
USGS scientists have previously warned that an earthquake stronger than magnitude 6.7 has a 95 percent chance of striking near the Bay Area (Pictured) by 2043
USGS’s earthquake forecast predicted that this impending earthquake had a 72 percent chance of striking right in the San Francisco Bay Area, home to approximately eight million people.
Overall, the grim report estimated that there was more than a 99 percent certainty that a major quake over magnitude 6.7 would erupt somewhere in the state, including Southern California, closer to Los Angeles and San Diego.
Researchers mentioned three specific fault lines running through Northern California that could trigger such a devastating event - the Hayward, Calaveras, and San Andreas faults.
While the infamous, 800-mile-long San Andreas has long been viewed as the likeliest seismic area which will unleash California's next major quake, the report concluded that the nearby Hayward and Calaveras faults currently have a higher chance of rupturing in the next two decades.
Researchers suggested that the northern portion of the San Andreas, near San Francisco, had less than a seven percent chance of producing a major earthquake because of its relatively recent activity during the 1906 mega earthquake.
That Bay Area earthquake along the San Andreas is believed to have reached magnitude 7.9, leaving 80 percent of the city destroyed and more than 3,000 people dead.
As for the latest swarm to rattle Californians near the Bay Area, there have been 26 minor quakes around The Geysers since 6pm Wednesday evening.
Smaller faults beneath this geothermal site have made the area prone to frequent earthquakes, and experts have said some tremors may be triggered by the region's geothermal energy operations, raising concerns about the potential for stronger shaking.
Dozens of earthquakes have been detected over the last day in an area known as The Geysers (Circled), a large geothermal field which lies atop a network of seismic faults
In late November 2025, the region just north of the Bay Area experienced at least 13 tremors on Thanksgiving, ranging from magnitude 1.0 to 3.7.
The Geysers are home to 18 geothermal power plants, and nearby residents can often feel the quakes beneath their feet.
Seismologists have said that as steam and heat are extracted from underground reservoirs, the surrounding rock contracts, creating stresses that can set off tremors.
Adding to the seismic activity, reclaimed water is pumped back into the steam chambers. The stark temperature difference between the cold water and the superheated rock can further destabilize the underground environment, producing even more quakes.
'It is possible that a magnitude 5 could occur, but larger earthquakes are thought to be unlikely. For a larger earthquake to occur, a large fault must exist,' the USGS said, and 'at the Geysers, no such continuous fault is known to exist.'
However, the Bartlett Springs Fault Zone and the Healdsburg–Maacama Fault system which sit under the geothermal field both branch out from the much larger San Andreas, which runs straight through the San Francisco Bay Area and into the Pacific Ocean.
