California residents experienced a wave of five earthquakes in the past 48 hours.
A 4.4 magnitude earthquake was felt in northern Lake County on Saturday, and two more hit the area the following night, measuring between 2.7 and 2.8 magnitude.
Southern California residents also reported two more earthquakes on Saturday, the largest measuring 3.9 magnitude.
Northern California typically sees a series of about 50 earthquakes a month, and two occurred this weekend, in addition to the two felt in the southern part of the state.
The swarm ranged in magnitude from 2.7 to 4.4, with the largest occurring at 7:00 a.m. ET on Saturday.
The 2.7 magnitude earthquake struck Covelo shortly after 12 p.m. Pacific time on Sunday and the second magnitude 2.8 earthquake occurred at 10:52 p.m. Pacific time that same day.
These reports came just a day after Southern California residents received a ShakeAlert, which notifies people of an impending earthquake and warns them to take cover, moments before it strikes.
The first had a magnitude of 3.5 on the Richter scale and occurred at 10:05 local time.
The epicenter was 4.3 miles southeast of Ontario, according to the U.S. Geological Survey.
The second, stronger quake, measuring 3.9 magnitude, occurred at 10:34 a.m., with its epicenter almost exactly in the same place.
The earthquakes were felt by millions of people across the area after they struck Saturday morning.
“I felt shaking early this morning between 6-7am, I thought in my sleep it was an earthquake and woke up this morning to see the news,” one person wrote on Reddit after Sunday’s quakes.
The U.S. Geological Survey has not reported any damage from the five earthquakes.
It’s rare for Northern California residents to notice earthquakes — most are magnitude three or less — but some people have reported feeling their homes shake due to seismic activity.
The U.S. Geological Survey (USGS) reported that people generally only feel earthquakes of magnitude 3.0 or higher, but it also depends on the depth and location of the earthquakes.
At their deepest levels, earthquakes can begin up to 400 miles underground.
Earthquakes reaching 43 miles or less are considered shallow and will only cause minor to moderate damage.
Residents received a ShakeAlert ahead of Saturday’s quakes, with one person saying they felt the tremor around 7 a.m.
However, 2024 has seen a record number of mini-earthquakes across the state and geophysicists are now warning that California could be at risk of a massive, generation-defining earthquake.
“In 2024 we’ve had more earthquakes than in any year since 1988,” Caltech geophysicist Dr. Lucy Jones told reporters. “We should expect this to continue.”
Experts believe a major earthquake in Southern California (generally defined as magnitude 7.0 or greater) could kill at least 1,800 people, injure 50,000 and cause more than $200 billion in damage.
The series of earthquakes came as a heat wave hit the state, leaving many people wondering if the record-breaking heat wave was to blame.
About 25 million residents faced heat alerts this weekend that stretched from California’s southern border to Washington and Idaho, but the USGS said it was not their fault.
“There is no such thing as ‘seismic weather,'” the USGS said.
‘Statistically, there is a roughly equal distribution of earthquakes in cold weather, warm weather, rainy weather, etc.’