A 4.4 magnitude earthquake struck 2.5 miles southeast of Highland Park at 12:20 p.m. Monday. In terms of intensity, the shaking was strong enough to knock items off shelves, but didn't cause any widespread damage.
It did startle quite a few people throughout the region.
About the quake
That's because the quake was centered right beneath a highly populated part of Los Angeles, meaning more people felt it than if the same size quake hit in a remote location.
As of 2 p.m., more than 20,000 people submitted "Did You Feel It" reports to the U.S. Geological Survey. Three aftershocks were recorded within a few hours of the main event, all smaller than magnitude 3.
- Did you feel it? Let USGS know ▶
The fault system
A number of foreshocks have been detected in the area over the past few months, but it's not clear which fault is responsible for today's quake. What is known is that the nearby Puente Hills fault could cause huge problems.
"There was a model that was done for a 7.5 on the Puente Hills thrust that ended up being five or ten times more damaging than a San Andreas earthquake because of so many people directly on top of it," seismologist Lucy Jones said at a news conference Monday. "That said, we have to remember that earthquakes on this fault system happen much less frequently than on the San Andreas fault."
Does this mean a bigger quake is coming?
There's a roughly 5% chance that a bigger quake could strike some time in the next few days. Although if it were to happen it'd likely only be slightly bigger than magnitude 4.4, according to Susan Hough, a seismologist with the U.S. Geological Survey.
Keep in mind that this is the standard forecast for all quakes, since the question comes up frequently.
An early warning was issued
The earthquake early warning system detected the quake 4 seconds after it started, calculated its size and issued warnings that were delivered by the app MyShake to more than 370,000 phones, according to Elizabeth Cochran, a seismologist with the USGS.
If you want to know when shaking is coming before it gets there, you can download the app.
What we know about reports of damage
At City National Plaza in downtown Los Angeles, the quake knocked sprinkler heads to the marble floor of the two story lobby.
At Pasadena City Hall, a water pipe burst and a person was briefly trapped in an elevator.
We have earthquake resources
We don't want to scare you, but the Big One is coming. We don't know when, but we know it'll be at least 44 times stronger than Northridge and 11 times stronger than the Ridgecrest quakes in 2019. To help you get prepared, we've compiled a handy reading list:
- Your guide to surviving the Big One
- For earthquakes, forget the 'go-bag.' Here's how to prepare
- How to not get life-threatening diarrhea after a major earthquake
- 10 earthquake-related questions to ask your landlord immediately
- How to prepare for an earthquake if you have a disability
- Listen to our podcast: The Big One: Your Survival Guide
