Earthquake Trio Hits SoCal Coast: How It Fits Into An Unusually Active Year For Quakes

LOS ANGELES, CA — A trio of earthquakes — the strongest of which was a magnitude 3.6 — struck off the Southern California coast over the weekend. The temblors came as the region has seen a dramatic uptick in larger quakes this year.

Sunday's maritime earthquakes were centered roughly between Dana Point and San Clemente Island, over 30 miles off the mainland coast. The first, a 3.2, hit at 4:11 p.m. It was followed by a 2.5 about five minutes later and a 3.6 at 5:32 p.m, according to data from the U.S. Geological Survey.

Shaking from the largest quake in the series was felt as far north as the San Fernando Valley, as far east as Lake Elsinore and as far south as El Cajon. The shaking was most intense along the coast, from Redondo Beach to Del Mar, according to reports submitted to the USGS.

The earthquakes came as Southern California has seen a dramatic increase in quakes of a magnitude 4.0 or above in 2024. As of mid August, there were 13 such earthquakes — nearly triple the average the state has seen over the last 20 years, seismologist Lucy Jones wrote on social media.

Another bigger quake, a 4.7 in Malibu, hit after Jones made her assessment. While that continued to make 2024 more of an anomaly compared to recent years, seismologists say the numbers are still within a normal range.

The average number of 4.0-or-larger quakes in Southern California since 1932 is around 10 or 12. It's the last 20 years, with around 5 such quakes, that's unusual, according to Jones.

"2024 is closer to normal than the quiet of the last two decades," Jones wrote.

Regardless, earthquake experts say there's no predicting when exactly the "big one" will hit.

There's two theories: that earthquake activity increases in an area before a large temblor — or that seismic activity decreases before a big quake, the Los Angeles Times reported.

However, SoCal remains at risk for a large, damaging earthquake of magnitude 6.0 or above because the region hasn't seen a quake of that significance in a long time — and faults are holding stress, USGS Earthquake Science Center geologist Stephen DeLong told SFGATE.

“The stress builds up, and the stress continues to build until it’s released,” DeLong said. Small earthquakes don’t help prevent the big earthquakes from happening, which is a common assumption. “It would take hundreds and hundreds of little earthquakes to release the amount of stress that’s released in a big one.”

Read more:

• 'Did You Feel It?' CA Quake Survivors Asked To Share Memories
• 72nd Quake In A Month Hit Malibu Wednesday — What It Means For The 'Big One'