California Rocked by Intense Earthquake Swarm, Heightening Fears of the ‘Big One’
Powerful Earthquake Swarm Rocks Southern California, Sparks Fears of "The Big One"
By Chris Melore, Assistant Science Editor for DailyMail.com
Updated: 19:05 BST, 11 July 2025
[Image: A map showing earthquake epicenters near the Salton Sea and San Andreas Fault.]
A series of earthquakes rattled Southern California overnight, igniting concerns about the looming threat of a catastrophic “Big One.” Six quakes struck near the Salton Sea, a region less than 100 miles from San Diego and close to the notorious San Andreas Fault.
Earthquake Swarm Details
The most powerful tremor, a magnitude 4.3, hit at 5:55 a.m. ET Friday. Earlier, three quakes between 4:18 a.m. and 4:22 a.m. registered above magnitude 2.5, strong enough to be felt locally. The swarm began Thursday evening with two quakes north of the Salton Sea at magnitudes 3.7 and 3.0.
[Image: Seismic activity chart highlighting magnitudes and times.]
All tremors occurred near the boundary of the Pacific and North American tectonic plates—a hotspot for seismic activity. The San Andreas Fault, capable of unleashing a magnitude 8+ earthquake, lies just 40 miles from the latest quakes.
The “Big One” Threat
Scientists warn that prolonged seismic swarms can stress nearby faults. “Each small quake slightly increases strain on adjacent segments,” explains Dr. Lucy Jones, a prominent seismologist. “The San Andreas hasn’t ruptured in over 300 years—it’s a question of when, not if.”
[Image: Diagram of tectonic plates and fault lines in California.]
A full rupture of the San Andreas could devastate cities like Los Angeles and San Francisco, causing billions in damage and disrupting critical infrastructure.
Why the Salton Sea Matters
The Salton Sea region has a history of triggering larger quakes. In 2016, a swarm near Bombay Beach preceded a magnitude 7.1 event in Ridgecrest. While experts caution that most swarms don’t lead to major disasters, the area’s proximity to the San Andreas keeps tensions high.
Residents are urged to update emergency kits and disaster plans. “Preparation saves lives,” reminds the USGS.
For live updates, follow DailyMail.com’s earthquake tracker.
[Image: Emergency kit checklist for earthquake preparedness.]
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