PASADENA -- A swarm of hundreds of earthquakes -- some registering magnitudes greater than 5 -- rattled Southern California along the Mexican border Sunday.
The ground below the town of Brawley near the Salton Sea could continue to rumble for several days, experts at the California Institute of Technology said.
The city of Brawley activated an Emergency Operations Center and many of its 25,000 residents were on edge into early evening, City Councilman Sam Couchman said.
"Residents were a little jumpy all day,"Couchman said."It's over 100 degrees, but many left their residences and stayed outside seekign any shade they could."
City officials spent a good portion of the assessing damage and battling rumors, Couchman said, "We had some minor damage," he said. "There were water line breaks...
We've had a little damage to windows on Main Street and a couple little trailers jumped off their foundations. Additionally there was plaster and facade damage in the downtown area."
Although Brawley's main hospital was evacuated for a time Sunday, no injuries were reported, Couchman said.
Schools, which were scheduled to open Monday will remain closed until all the damage can be assessed, Couchman said.
Sunday's series of more than 200 earthquakes, which scientists refer to as a swarm, all emanated from a small stretch of fault line about three to four kilometers long near Brawley, about 16 miles north of El Centro, according to Lucy Jones a United States Geological Survey seismologist.
"It's characteristic of the seismology of the Imperial Valley," she said.
While tremors larger than the 5.3- and 5.5-magnitude earthquakes felt Sunday were not expected in coming days, "It's always a possibility,"
Locals spent much of Sunday afternoon cleaning up the mess.
Cynthia Rivera, an employee of Brawley's Tai San Chinese Restaurant, said a television crashed to the floor but there was very little other damage at the extablishment.
Rivera described the quake activity as "really strong."
As for her customers, most residents of Brawley, all were talking about the quakes Sunday night.
"Some people lost electricity at home, there was some damage to plasma TVzs and furniture and everybody was excited."
Abby Campos, an employee of the Best Western in Brawley, said a quake that struck about 10 a.m. "lasted a good time. It wasn't brief."
Guests at the hotel, including some from out-of-state, were evacuated as a precaution, she said.
"Most were advised to seek another place to stay," Campos said.
"Several guests who never felt a quake before said they just wanted to go home."
A native of Brawley, Campos said residents expect quakes around this time of year.
"We usually experience them during the time change and it's that time of the year again," she said.
Some shaking was felt at Del Mar where horse race fans were gathered to wager on the day's thoroughbred races in the San Diego County coastal town, about 120 miles from the epicenter. The quake was felt from the Coachella Valley to Orange County and northern MExico, officials said.
Earthquake swarms are known to occur in the area near California's southern border, though the reason remains the subject of scientific study, Jones said.
It's believed that the swarms are due to magma movement in heavily saturated ground, such as seen in the Imperial Valley.
The region is known as the Brawley Seismic Zone, Jones explained.
Lined with small fault lines, it sits between the San Andreas Fault and Imperial Fault Zones.
The first quake of the swarm had a magnitude of 3.9 and hit at 10:02 a.m. It was followed by a smaller quake about 90 seconds later in the same area near the southern end of the Salton Sea, and other smaller quakes followed within six minutes of the first shock.
By afternoon, more than 200 earthquakes had been recorded by the USGS, and continued into the evening. Sixteen of the quakes had a magnitude between 4.0 and 4.9, and another 16 registered magnitudes between 3.0 and 3.9, Jones said. The vast majority of the quakes were well below 3.0-magnitude.
Portions of the Brawley Seismic Zone have seen activity in the past decade, Jones said. It's most significant recent activity was recorded in the 1970s.
The Associated Press contributed to this story