At least 100 aftershocks have been reported in the hours after Sunday afternoon's magnitude-7.2 earthquake near the California-Mexico border. More aftershocks -- some in the 5.0- to 6.0-magnitude range -- are expected to shake Southern California this week.
"If you felt the first earthquake strongly, it's likely you will feel the aftershocks," said Caltech's Dr. Lucy Jones. "It's likely they will happen over the next few days. The chance of a magnitude-5.0 to 6.0 aftershock is pretty good."
The U.S. Geological Survey timeline shows a swarm of aftershocks and other earthquakes. Caltech's Kate Hutton said early Monday that aftershocks became less frequent overnight.
Local news from across Southern California
Right on cue, Hutton received a text as she spoke at a Monday morning news conference -- it was yet another aftershock. The magnitude-5.0 aftershock occurred at about 6:33 a.m. about 70 miles east of Tijuana.
"I don't think we can expect much here, but I think people in the Imperial area, near the epicenter, in the San Diego area might experience more earthquakes," Hutton said.
The quake's epicenter was located about 30 miles south of Mexicali, about 120 miles east of San Diego. The quake struck at 3:40 p.m. Initial reports said the quake was magnitude-6.9, but officials with the USGS later changed the figure to 7.2.
The quake rattled northern Mexico, Southern California and southwest Arizona.
"It sounds like it's felt by at least 20 million people at this point," USGS seismologist Dr. Lucy Jones said. "Most of Southern California felt this earthquake."
The quake set high-rise buildings in Riverside, Los Angeles and San Diego rocking back and forth. It also was felt in Palm Springs, but significant damage was not reported in Southern California.
"Being this far away it would have been a rolling motion," said Jones, of Caltech. "All the high energy is gone by the time it gets here."
The rolling motion was felt as far north as Santa Barbara, USGS seismologist Susan Potter said. The earthquake was also felt in Phoenix and Las Vegas, according to reports.
Susan Warmbier was putting away her groceries in the San Diego suburb of Chula Vista when her husband asked, "Is the house moving?"
"We turned and we looked at the house, and it was actually moving," she said. "You could see it slightly moving left to right."
Jean Nelson, who was in Indio during the quake, told Reuters, "I'm shaking like a leaf ... the pool water was just going everywhere."
The quake provided an unepected ride for visitors at Disneyland.
There were no power outages anywhere in the city, said Los Angeles Department of Water and Power spokeswoman Maryanne Pierson. A preliminary report indicated there was no significant damage in Los Angeles.
Los Angeles Fire Department officials inspected buildings and overpasses for damage.
Fatality, Damage in Mexicali Area
Baja California state Civil Protection Director Alfredo Escobedo said the quake killed a man whose home collapsed in northern Mexico, according to the Associated Press. Authorities told the LA Times that a second man was killed when he ran into the street during the shaking and was struck by a vehicle.
Movement was felt for about 40 seconds in Tijuana, Mexico, causing buildings to sway and knocking out power in parts of the city. The Associated Press reported that families celebrating Easter ran out of the homes, with children screaming and crying.
The LA Times reported that at least six homes burned outside Mexicali after propane tanks ruptured.
Tijuana Fire Chief Rafael Carillo said firefighters so far have responded only to reports of minor damage. Near the epicenter, receptionist Juan Carlos Fernandez said there was minor damage at the Crowne Plaza hotel in Mexicali. The damage includes broken pipes and windows.
Nearly 80 percent of the buildings in the historic downtown area were red-tagged.
Calexico Fire Chief Peter Mercado said there is substantial damage in the older section of the city. Mercado said there is structural damage and broken windows, leaking gas lines and damage to the water system. But he says no injuries have been reported.
The quake could be devastating for the economy of Imperial County, which already has the highest unemployment rate in the state, said Hildy Carrillo, executive director of the Calexico Chamber of Commerce.
"It will be months before downtown is back. It's a mess," she said.
Several aftershocks have hit the area. A magnitude-4.9 aftershock struck the region Monday night.
Seismologists Eye Laguna Salada Fault
Jones said it's possible the fault involved was the Laguna Salada fault. It triggered a magnitude-7.2 earthquake in 1892.
"This might be a repeat for it, but we really need to get out there and see," Jones said.
Seismologists said the quake was the largest to strike the region in 18 years.
Jones compared Sunday's earthquake to the 1992 magnitude-7.3 Landers earthquake. The quakes were not on the same fault, but it was after the Landers quake when seismologists realized a major earthquake can trigger earthquakes in other areas.
Three fatalities were attributed to the Landers quake.
Earlier this weekend, a series of small-to-moderate quakes hit the geothermally-active area.
An earthquake with a preliminary magnitude of 4.0 was recorded in Northern California on Sunday afternoon. The quake hit at 3:49 p.m., about 25 miles north of Santa Rosa, according to the USGS. A geophysicist with the U.S. Geological Survey said the earthquake recorded in Northern California was not related to the Mexicali quake.
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