Southern California is experiencing increased seismic activity, with two significant earthquakes in less than two days near Johannesburg in Kern County, raising concerns among some experts about the possibility of a major seismic event, often referred to as "The Big One."
On Monday, a 4.3-magnitude tremor struck the area around 9:40 a.m. PST, less than 24 hours after a 4.1-magnitude earthquake occurred in the same location. While no injuries or property damage were reported, the repeated seismic events have drawn the attention of geophysicists.
Stefan Burns, a California geophysicist, noted that these earthquakes occurred at the intersection of the San Andreas Fault and the Garlock Fault. He stated on X that the recent tremors represent the "highest magnitude event" in that specific juncture in 26 years. Burns has previously warned in a YouTube video that an earthquake at this junction could potentially trigger a larger event by leaping from the Garlock to the San Andreas Fault.
Burns explained that both the San Andreas and Garlock faults are "strike-slip faults," where tectonic plates slide past each other. However, he noted that these plates can sometimes interlock, leading to a buildup of immense pressure over decades or centuries. The eventual release of this pressure could result in a major earthquake with a magnitude of 7.5 or higher, affecting Southern California.
"We already know that the Garlock is locked and loaded for a big rupture," Burns warned. "Could be magnitude 7 or higher, magnitude 7.5 or greater even." He added that both fault lines are considered overdue for significant seismic activity.
However, not all experts share this immediate concern. Some observers from the Southern California Seismic network suggested that the recent tremors may have occurred on the Pleito Fault, a less prominent fault situated several miles away from the Garlock-San Andreas junction. Additionally, some seismologists maintain that earthquakes of this magnitude are relatively common and do not necessarily indicate an impending larger tectonic event.
It is also considered normal for aftershocks to continue for days or weeks following an earthquake, according to experts.
Despite differing interpretations of the recent seismic activity, experts caution against complacency. A study published last month indicated that stress levels along the San Andreas and San Jacinto faults, two of California's most hazardous fault lines, have reached their highest point in at least 1,000 years. A magnitude 7 or larger earthquake in this region could impact approximately 24 million people and disrupt critical infrastructure, including transportation and energy systems.
In related seismic news, a 5.6 magnitude earthquake previously struck Mendocino County in Northern California, triggering numerous early-warning alerts and causing some power outages and damage. That event also resulted in minor injuries and thousands of dollars in damage.