California Shaken by Earthquake Swarm Along San Andreas Fault — Is the "Big One" Looming?

Over the past 24 hours, California has been rattled by a series of earthquakes that have reignited fears about the long-anticipated "Big One" — a massive, potentially catastrophic seismic event scientists say is overdue along the San Andreas Fault.

According to the U.S. Geological Survey (USGS), three minor earthquakes were detected within a short span of time, with magnitudes ranging from 2.5 to 2.9. While these tremors were too small to cause significant damage, they occurred in an area of intense geological concern: the San Andreas Fault system, a massive fault line stretching roughly 800 miles across the Golden State.

The initial quake struck Thursday afternoon northeast of San Francisco, along the Calaveras Fault — one of the major branches of the San Andreas system. Two more followed Friday morning, one directly on the San Andreas and the other along another associated fault. Although no injuries or damage have been reported, the cluster of quakes has prompted heightened awareness among seismologists and residents alike.

For decades, scientists have warned that California is due for a major quake along the San Andreas Fault, with estimates suggesting a magnitude 7.8 or higher event could occur within the next 30 years. Historical patterns indicate the fault tends to rupture with significant force approximately every 150 years — and it’s been 167 years since the last major rupture in Southern California, the 1857 Fort Tejon earthquake.

That quake registered a massive 7.9 in magnitude and left a path of destruction across Southern California, uprooting trees, opening ground fissures, and causing fatalities. Similarly, the 1906 San Francisco earthquake — also a 7.9 magnitude — devastated the city and resulted in around 3,000 deaths.

The recent swarm of quakes has raised questions once again about whether there are signs pointing to an imminent large-scale event. Dr. Sue Hough from the USGS Earthquake Hazards Program cautioned that while some studies suggest increased seismic activity may precede a major quake, others have found no reliable patterns.

Adding to the broader seismic risk, scientists are also closely monitoring the Cascadia Subduction Zone, another powerful fault located off the northern California, Oregon, and Washington coasts. A major quake there — estimated to reach magnitude 8.0 or higher — could not only shake the region but also cause widespread land subsidence and coastal flooding, affecting thousands of residents and structures.

With both the San Andreas and Cascadia faults showing signs of potential activity, experts continue to urge awareness and preparedness. Though the exact timing of a large quake remains impossible to predict, the growing body of data suggests that California’s most powerful natural threats are far from dormant.

Stay informed. Stay alert.

Source: Daily Mail