Californians woke up to a jolt on Monday as a series of earthquakes shook the northern part of the state.
The tremors came in rapid succession, leaving residents and scientists alike keeping a close eye on the region.
The Tremors and Their Magnitude
According to the US Geological Survey (USGS), there were at least seven noticeable quakes, ranging from minor 1.1 magnitudes to a more significant 4.1 magnitude. The strongest hit at 7:08 a.m. Pacific Time near The Geysers, a geothermal hotspot in the Mayacamas Mountains.
The remaining tremors were likely aftershocks.
Residents reported feeling the shaking as far south as San Francisco, with some describing their homes rattling and objects shifting.
The Geysers: Not Your Typical Geyser
Despite its name, The Geysers doesn’t feature erupting water fountains.
Early settlers misnamed the area after seeing steam vents, known scientifically as fumaroles.
Stretching across Sonoma, Lake, and Mendocino counties, this geothermal field spans roughly 45 square miles and powers 18 plants that generate electricity from underground steam.
Fault Lines and Seismic Risk
The region sits atop a complicated network of faults, including the Bartlett Springs Fault Zone and the Healdsburg–Maacama Fault system.
These smaller faults make the area naturally prone to frequent quakes.
Experts say that geothermal operations—like pumping steam and re-injecting water—can sometimes trigger additional tremors.
As steam is drawn out of underground reservoirs, surrounding rock contracts, creating stress that can lead to earthquakes.
Adding cold reclaimed water back into the chambers can further destabilize the system due to temperature differences with the superheated rock.
What the Experts Say
While minor quakes are common, the USGS notes that a quake exceeding magnitude 5 is possible but unlikely.
“For a larger earthquake to occur, a large continuous fault must exist, and at The Geysers, no such fault is known,” the agency said.
California’s Seismic Reality
California ranks as the third most seismically active state in the U.S., behind Hawaii and Alaska.
The state has seen more than 14,000 tremors so far this year.
While Alaska experiences a higher number of quakes overall, California faces greater risk for damage because of its dense population and extensive infrastructure.
Staying Prepared
Residents near The Geysers are accustomed to feeling minor tremors.
With geothermal operations continuing in the area, scientists emphasize vigilance but reassure that catastrophic quakes remain unlikely.
California continues to balance its energy production with seismic safety, keeping an eye on both the ground beneath and the population above.
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