A San Diego-based geology expert said that while Friday’s 5.2-magnitude earthquake near Borrego Springs may be part of an interesting series of seismic movements, the event was a “common Southern California quake.”
“This is your classic fault movement, followed by a number of smaller ones that will likely die off,” Patrick Abbott, Ph.D, and Professor Emeritus of Geology at San Diego State University (SDSU), told NBC 7.
Abbott said there’s a slight chance the earthquake may have been a foreshock but he estimates the likelihood of this – and of a larger quake striking soon in the region – is 2 to 4 percent.
The quake, which was felt throughout Southern California, including in San Diego County, struck at 1:05 a.m. The United States Geological Survey (USGS) said its epicenter was 13.7 miles northwest of Borrego Springs, a community located about 90 miles northeast of downtown San Diego.
Abbott told NBC 7 the quake happened along the San Jacinto Fault Zone, the most active zone in Southern California in the 21st Century.
“[It’s the] least surprising source of earthquakes to Southern California,” he added.
He said the quake was the result of a six-mile-deep, two-mile-long section of earth rupturing and moving, shoving energy northward. Abbott described the tear as moving much "like a zipper."
As of 8:10 a.m., at least eight smaller aftershocks had hit the region, including 3.5-magnitude quake at 4:14 a.m., according to the USGS.
Abbott said the series of aftershocks are standard for a quake of this size and the strongest aftershocks linger for about 72 hours.
“You never have just one earthquake,” he explained. “An earthquake is actually a series of movements along a fault that can take place for weeks and months.”
Abbott said geology experts have zero ability to tell the day or even year when “The Big One” might strike. In this case, he said it’s possible a quake in the 6 or 7-magnitude range could follow, but it’s unlikely.
He said he sees “no pattern whatsoever” with this quake.
Abbott said, in geological terms, a 5.2-magnitude earthquake like Friday’s event could be considered to be in the “fun zone.”
“Everybody gets to feel it and learn from the experience, but we don't really have damages or injuries or anything of that sort,” he explained.
Abbott said the earthquake struck on the west side of the Santa Rosa Mountains, away from homes. He said the energy from the waves had to travel to reach more populated areas, which impacted the way it was felt by those across different parts of Southern California.
He said that when energy is released from an earthquake, seismic waves come out at different frequencies. Being close to the epicenter, residents in Borrego Springs likely felt those waves strongly.
“Not everyone feels the same effects,” Abbott told NBC 7. “A lot of other factors either magnify or reduce the energy people feel [from an earthquake].”
Many NBC 7 viewers reported feeling the earthquake across their communities including Ramona, La Mesa, Escondido, Poway, Tierrasanta, Santee, Mission Valley, Mira Mesa, Valley Center, Ocean Beach, Chula Vista, El Cajon, Carlsbad and Vista.
The County of San Diego Office of Emergency Services (OES) said Friday’s earthquake is a reminder for residents to prepare themselves for possible natural disasters by making a plan, building an emergency kit and staying informed.
OES director Holly Crawford said there are several easy and inexpensive things people can do in preparation for emergencies such as earthquakes. This includes assembling an emergency kit that includes water, food, a flashlight, important documents, a first aid kit, a radio and batteries.
Residents should also map out an emergency plan that includes a meet-up point for your family in case you’re separated when a quake hits.
The OES preparedness website, Ready San Diego, offers additional tips. The information is also available in Spanish here. Residents can also sign up for AlertSanDiego, the region’s mass notification system to get updates from authorities during emergencies.
In case of a quake, Abbott said it’s important to remember this: “Earthquakes don’t kill – buildings do.”
He said you should never run during an earthquake, as shifting objects could hurt you.
“[If you run], you’re a moving target. You don’t want to be running, you want to be under something so when things fall, they can’t hurt you,” he explained. “Where are you running to?”
Abbott said overnight hours – such as this 1:05 a.m. incident – is a good time for a quake to strike, as most people are asleep under the covers, without shelves or bigger pieces of furniture hanging over them.
“The safest place in the world for you to experience an earthquake is lying in bed,” said Abbott. “The only problem you could have is if you put something close enough to you, it could fall on you.”