California experienced four earthquakes in less than 12 hours, according to the US Geological Survey (USGS). The seismic activity began around 9pm ET on Wednesday with a 3.5 magnitude quake near Little Lake, followed by a 2.8 magnitude event at 4:30am near Petrolia in northern California.
A 2.7 magnitude earthquake was also detected at 4:55am along the San Andreas fault northwest of San Diego. No injuries or damages have been reported from any of the quakes.
According to Michigan Tech University, earthquakes of magnitude 2.5 or less are typically not felt, while those between 2.5 and 5.4 are often felt but cause only minor damage.
The quakes occurred along the San Andreas fault, which experts fear is overdue for a major earthquake. The last major earthquakes on the fault were the 1857 Fort Tejon earthquake (magnitude 7.9) and the 1906 San Francisco earthquake (also magnitude 7.9), which killed 3,000 people.
California has recorded more than 11,000 earthquakes this year, with nine above magnitude 2, according to Volcano Discovery. The 'Big One', a magnitude 8 or higher, is estimated to affect over 39 million people on the West Coast.
