(CTN News) – Several earthquakes occurred following an earthquake measuring 4.8 magnitude that struck near El Centro in Imperial County, east of San Diego, early Monday morning.
According to the USGS, 1.8 miles north-northwest of El Centro was the location of at 12:36 a.m. The epicenter was roughly 11.7 miles below ground.
A total of 12 more 2.5-magnitude or greater were reported between 12:38 and 1:01 a.m. near El Centro and Imperial, according to the USGS. An aftershock of 4.5 magnitude struck at 12:42 a.m., north of El Centro.
As the morning progressed, the earthquake swarm continued. At 6:35 a.m. on Monday, 23 quakes with a magnitude of at least 2.5 rattled the area. At 6:34 a.m., a magnitude 2.5 earthquake hit about half a mile southeast of El Centro.
On the USGS’s “Did You Feel It?” map, San Diego County residents reported feeling the initial quake in Alpine, Chula Vista, Coronado, Imperial Beach, La Mesa, Oceanside, Poway and Santee. Even Aliso Viejo, Orange County, was shaken by the shaking in Yuma, Arizona, and Palm Desert, Riverside County.
ShakeAlert Earthquake Early Warning System was activated by the earthquake, which detects significant quakes early enough to alert residents and automated systems potentially seconds before shaking begins. As a result of the USGS’s early warning system estimating the quake to be above magnitude 5.0, cell phone alerts were sent through apps such as My Shake and Shake Ready SD.
By 7:38 a.m. Monday, the Southern California Seismic Network had recorded 187 “events” in the swarm, the smallest measuring 0.9 magnitude.
Many smaller earthquakes are still being analyzed and gradually being added to the catalog, according to the Southern California Seismic Network. Southern California is expected to experience more swarm activity in the coming days. Swarm activity may last hours, days, weeks, months, or years.
The National Tsunami Warning Center reported no tsunami danger from the quakes.
According to a statement issued Monday by the California Governor’s Office of Emergency Services, the state is closely monitoring the impacts of and aftershocks and continues to work with partners to assess any damage.
Southern California was hit by one of the most powerful earthquake swarms in recent memory.
There had also been a smaller swarm of quakes after the magnitude 4.6 quake near Malibu two days earlier.
There were no injuries or property damage reported.