California Has Been Struck by Seven Earthquakes in Under 24 Hours

California has been struck by seven earthquakes in under 24 hours, with the most recent tremor occurring on Friday morning.

According to data from the US Geological Survey (USGS), five of these seismic events were recorded along the San Andreas Fault, a region that geologists warn is long overdue for a catastrophic earthquake measuring 8.0 or greater, often referred to as the 'Big One.'

The first quake, measuring 2.7 in magnitude, was detected off the coast of Northern California on Thursday. Less than an hour later, a second tremor of 2.5 magnitude shook the same area.

By Friday, another earthquake, this time measuring 2.9, occurred near the initial cluster. Additionally, a 2.7-magnitude quake was recorded northwest of San Diego, followed by the latest event, a 2.6-magnitude tremor.

The remaining two earthquakes were registered in the Death Valley area, along the Foothills fault system. One of these, measuring 3.0, occurred on Friday, while the other, a 2.6-magnitude quake, was recorded on Thursday.

A study by Michigan Tech University notes that tremors below a magnitude of 2.5 generally go unnoticed by people. Earthquakes ranging between 2.5 and 5.4 are often felt but rarely cause significant damage.

Authorities have not reported any injuries or structural damages from this recent seismic activity in California.

The earthquake sequence generated only minor tremors, with a limited number of reports submitted to the USGS. Although none of these quakes were classified as severe, over half of them took place along the San Andreas Fault, a major geological boundary stretching 800 miles from Cape Mendocino in the north to the Salton Sea in the south.

According to projections from the Great California ShakeOut, a potential 'Big One' could result in approximately 1,800 fatalities, 50,000 injuries, and economic losses reaching $200 billion.

Historical records indicate that the last significant earthquakes along the San Andreas Fault occurred in 1857 and 1906.

The 1857 Fort Tejon earthquake, a 7.9-magnitude event, caused surface ruptures along the Los Angeles, Santa Ana, and Santa Clara Rivers. The quake led to extensive damage, with trees uprooted, buildings demolished, and two casualties reported.

Similarly, the devastating 1906 San Francisco earthquake, also measuring 7.9 in magnitude, resulted in approximately 3,000 deaths and widespread destruction throughout the city.

Experts continue to monitor seismic activity, with some predicting that a powerful earthquake is likely within the next three decades. "Experts are 'fairly confident that there could be a pretty large earthquake at some point in the next 30 years,'" stated Angie Lux, a project scientist at the Berkeley Seismology Lab's Earthquake Early Warning program.

Dr. Sue Hough, a scientist with the USGS Earthquake Hazards Program, explained to KTLA5 that researchers hold differing opinions regarding earthquake precursors. "Some research suggested more activity happens before it hits, while others have found there is no warning," she noted.

Data from Volcano Discovery indicates that California has recorded over 6,200 earthquakes this year, with magnitudes reaching up to 4.7. Of these, around four exceeded magnitude 4, while approximately 5,800 were below magnitude 2.

Most earthquakes originate from the continuous movement of tectonic plates, which form Earth's outer shell. These massive rock slabs shift atop the planet’s mantle, occasionally becoming stuck due to friction. As pressure builds, the accumulated stress is eventually released, generating seismic waves that cause surface shaking.

The Foothills fault system, located in the Sierra Nevada mountains, lies several miles away from the San Andreas Fault. The last major seismic events in this region occurred in 1975 near Oroville, as well as in 1909 and 1888 near Nevada City. These earthquakes had magnitudes ranging from 5 to 6.