A 5.2 magnitude earthquake struck southern California this morning, startling residents across San Diego County. The quake hit at 10:08 AM (PDT) on Monday, April 14, 2025, with an epicenter about 4 km (3 miles) south of Julian, CA, in the mountains east of San Diego (5.2 earthquake shakes the southland – Village News). Shaking was felt strongly around San Diego County — reports came in from the city of San Diego out to the suburbs, and even as far north as Riverside County (5.2 earthquake shakes the southland – Village News). The quake originated at a depth of roughly 13 km (8 miles) underground, which is relatively shallow and contributed to it being widely felt (5.2 earthquake shakes the southland – Village News). Fortunately, as of the latest updates, no major damage or injuries have been reported in the region (Large earthquake jolts area near San Diego – ESPN 690). The USGS ShakeAlert early warning system was triggered by the quake, meaning some locals got a few seconds of warning on their phones before the shaking arrived (Large earthquake jolts area near San Diego – ESPN 690) – a reminder that these new alert systems are in action.
Map showing the earthquake’s location just south of Julian and several aftershocks in the same area. Julian is a mountain town in eastern San Diego County, and the surrounding fault zones produced a cluster of tremors.
Why Did the Earthquake Happen?
Southern California sits near the boundary between two massive tectonic plates – the Pacific Plate and the North American Plate. These plates are slowly sliding past each other, crisscrossing the region with active fault lines. This morning’s Julian earthquake occurred along the Elsinore Fault Zone, one of the major strike-slip faults running through San Diego County (5.2 mag earthquake followed by at least 10 aftershocks near San Diego). In case you’re wondering, this was not on the San Andreas Fault. The San Andreas Fault proper lies farther east; instead, the Julian quake struck on the Elsinore Fault, a branch of the San Andreas system. The Elsinore Fault Zone runs through inland San Diego and has a history of producing moderate quakes – in fact, it’s capable of quakes in the magnitude 6.5 to 7.5 range in a worst-case scenario (Large earthquake jolts area near San Diego – ESPN 690).
What caused it? In simple terms, stress had been building up along the fault as the plates slowly moved. When the stress overcame the friction locking the fault in place, the rock slipped suddenly – releasing energy in the form of seismic waves. That sudden slip is what we felt as an earthquake. Geologists refer to the spot on the fault that ruptured as the epicenter (in this case just south of Julian), and the depth (~13 km down) as the hypocenter where the rupture began (5.2 earthquake shakes the southland – Village News). This was a strike-slip earthquake, meaning the ground on either side of the fault lurched horizontally past each other. The orientation and exact fault segment will be studied, but being in Julian’s vicinity strongly points to the Elsinore Fault Zone as the culprit.
Aftershocks and the Chance of a Bigger Quake
It’s normal for a swarm of aftershocks to follow a moderate quake like this. And indeed, seismologists have already recorded a series of smaller quakes rattling the area in the aftermath (5.2 mag earthquake followed by at least 10 aftershocks near San Diego). In the first hour after the mainshock, at least 10 aftershocks have been noted, with magnitudes ranging from the mid-2’s up to about 3.5 (5.2 mag earthquake followed by at least 10 aftershocks near San Diego). Most of these have been centered in the same general area south of Julian (some just a few miles away, one about 7 km east near Borrego Springs). You might feel some of the stronger aftershocks if you’re nearby, or you may not notice the smaller ones at all. The number of aftershocks will taper off over time, but they could continue for days or even weeks (getting progressively weaker). Expect some rumbles in the coming days – that’s just the Earth readjusting to the new stress state after the main event.
A common question locals ask is: “Is this a sign of a bigger earthquake coming?” In most cases, the answer is no – most quakes are not precursors to something larger. According to the USGS, worldwide there’s only about a 5% chance that any given earthquake will be followed by an even larger earthquake within the week (What is the probability that an earthquake is a foreshock to a larger earthquake? | U.S. Geological Survey). In other words, 95% of the time, the first quake is the mainshock and anything after it is smaller. So the odds are strongly in our favor that this morning’s M5.2 quake near Julian was the main event and not a trigger for an imminent “Big One.” Of course, it’s not impossible for a bigger quake to follow – it’s just unlikely. Seismologists will keep a close eye on the activity. For now, what we’re seeing are typical aftershocks. (Interestingly, a small foreshock may have happened yesterday: an earthquake of about magnitude 3.5 shook the same area on Sunday afternoon (Large earthquake jolts area near San Diego – ESPN 690). We only recognize it as a foreshock in hindsight, because it was followed by a larger quake. There was no way to know at the time that the 3.5 would precede a 5.2 – a reminder of how unpredictable quakes can be.)
To recap: aftershocks will continue (so don’t be surprised if you feel a few more jolts), and a much larger quake triggered by this event is not very likely. Still, Southern California is earthquake country – it’s always good to stay prepared just in case.
Earthquake Safety Reminders
Earthquakes can be unnerving, but knowing what to do can help you stay safe. Here are some quick safety tips for before, during, and after a quake:
- During the shaking: Remember to Drop, Cover, and Hold On (Drop, Cover, Hold On | U.S. Geological Survey). Drop to the ground, take cover under a sturdy table or desk (or against an interior wall away from windows), and hold on until the shaking stops. If you’re indoors, stay inside – do not run outside during the shaking. Stay away from windows or heavy furniture that could fall. If you’re outside, move to an open area away from buildings, trees, streetlights, and power lines (Earthquakes | Ready.gov). In bed, protect your head with a pillow. If driving, pull over and set the parking brake.
- After the shaking stops: Expect aftershocks – it’s normal to have many smaller quakes following the main shock (Earthquakes | Ready.gov). Be ready to Drop, Cover, and Hold On again if another shake hits. Check for injuries or hazards once it’s safe: there could be serious hazards after an earthquake, such as gas leaks, water line breaks, or downed power lines (Earthquakes | Ready.gov). If you smell gas or see fire, shut off the gas if possible and evacuate the building. Use flashlights instead of candles (to avoid igniting gas). Avoid damaged structures – if your home or building has visible damage, be cautious and consider evacuating until it can be inspected (Earthquakes | Ready.gov). Keep shoes on to avoid stepping on broken glass.
- Stay informed: Turn on a battery-powered radio or use your phone (if service is available) to get news updates. Authorities will broadcast important information if there are any significant developments or emergencies.
- Be prepared (beforehand): Let this quake be a reminder to update your emergency kit and plans. Every San Diego household should have an earthquake preparedness kit with essentials: food and water for several days, a flashlight, a fire extinguisher, a first-aid kit, a whistle, and other necessities (Earthquakes | Ready.gov). Keep the kit in an easily accessible place. Also, have a family emergency plan – decide on a meeting point and an out-of-state contact for everyone to check in with (Earthquakes | Ready.gov). Being prepared ahead of time means you’ll be better off when the next quake (or any disaster) strikes.
“Did You Feel It?” – How to Report the Quake
If you felt the earthquake, you can help scientists and fellow citizens by reporting your experience on the USGS “Did You Feel It?” website. Did You Feel It? (DYFI) is a citizen science program that collects information from people who felt an earthquake and creates maps showing what people experienced and the extent of damage (Did You Feel It?). It only takes a minute to fill out the survey: you’ll be asked where you were, what you felt, and if there was any damage. These reports are extremely useful – they help create a crowd-sourced intensity map for the quake, showing how far the shaking was felt and how strong it was in different areas.
To report, visit the USGS earthquake event page for the Julian quake (or go to the USGS Did You Feel It? page and find the event). Many San Diegans have already shared their “felt” reports – joining in will give scientists a fuller picture of this earthquake’s reach. Plus, it’s kind of neat to see your experience become a data point on the map!
In summary, this San Diego-area earthquake gave our region a good rattle, but it wasn’t catastrophic. Knowing the basic facts (5.2 magnitude, Julian epicenter, 13 km deep (5.2 earthquake shakes the southland – Village News)) and understanding why it happened (slip on the Elsinore Fault, not the San Andreas (5.2 mag earthquake followed by at least 10 aftershocks near San Diego) (Large earthquake jolts area near San Diego – ESPN 690)) can help demystify the event. We can expect some aftershocks but likely nothing worse, as large follow-up quakes are rare (only ~5% chance of anything bigger soon (What is the probability that an earthquake is a foreshock to a larger earthquake? | U.S. Geological Survey)). Take this opportunity to refresh your earthquake safety knowledge and preparedness kits. And if you felt it, don’t forget to let the USGS know through “Did You Feel It?” (Did You Feel It?). Stay safe, San Diego!
