California was shaken early Thursday as a series of earthquakes struck in quick succession, raising concern in the seismically active region.
The US Geological Survey (USGS) reported six tremors ranging in magnitude from 2.6 to 4.0.
The seismic activity began at 1:51am ET, when four quakes occurred within just two minutes. Magnitudes ranged from 2.6 to 4.0.
These quakes, roughly 72 miles north of San Francisco, struck near the San Andreas Fault, a massive 800-mile tectonic boundary stretching from Cape Mendocino to the Salton Sea.
Scientists have said that this fault is considered overdue for a ‘Big One,’ a magnitude 7.8 earthquake or higher, making the recent activity closely monitored.
The Maacama Fault, running north of Santa Rosa up to Ukiah, experienced a 3.9 magnitude quake.
This parallel fault system adds complexity to the region’s seismic activity, with experts suggesting the events may be part of a swarm or aftershock sequence.
And the latest tremor, a 3.6 magnitude, was detected in Southern California around 9:50am.
This is a developing story… More updates to come.
An assessment from Michigan Tech University showed that people typically do not feel quakes with a magnitude of 2.5 or less.
Those from 2.5 to 5.4 are often felt but only cause minor damage.
Residents reported light shaking, but no significant damage or injuries have been reported.
Scientists have long kept a close eye on the San Andreas fault, fearing it could soon release a devastating earthquake.
A 7.8 magnitude tremor could cause roughly 1,800 deaths, 50,000 injuries and $200 billion in damages, according to the Great California Shakeout.
Based on historical trends, it’s estimated that the San Andreas causes a major quake every 150 or so years, and the last one was 167 years ago.
The vast majority of earthquakes result from the constant movement of tectonic plates, which are massive, solid slabs of rock that make up the planetary surface and shift around on top of Earth’s mantle — the inner layer between the crust and core.
As the tectonic plates slowly move against each other, their edges can get stuck due to friction and stress will build up along the edges.
When that stress overcomes the friction, the plates slip, causing a release of energy that travels in waves through the Earth’s crust and generates the shaking we feel at the surface.
