A strong earthquake, measuring 6.3 on the Richter scale, jolted the Imperial Valley early Tuesday morning, injuring 94 people in the United States and Mexico and damaging some structures. It came just 12 hours after a quake of slightly smaller magnitude struck the same area.
Across the border in the town of Mexicali the Red Cross said a mother and child were killed when they fled a downtown factory during the temblor and were struck by an automobile.
Fifty people were treated for injuries in Mexicali and 44 in Imperial County. Most of the injuries were minor.
The quake was the strongest in California since the Coalinga earthquake of May 2, 1983, which was 6.7 on the Richter scale. The quake hit at 5:16 a.m. and was felt as a rolling motion across Southern California and as far east and north as Phoenix and Las Vegas.
The epicenter of the shock, like the 6.0 quake that struck Monday evening and its numerous aftershocks, was in a lightly populated desert area. Tuesday’s epicenter was 14 miles southwest of the small community of Westmorland in Imperial County.
Its distance from populated areas kept damage and injuries down compared to the severe disruption caused by the Oct. 1 Whittier Narrows earthquake, which was only about half as strong but was centered in heavily populated parts of the San Gabriel Valley just east of Los Angeles.
Still, authorities reported that 20 people were treated for various injuries at the El Centro Regional Medical Center and another 20 at El Centro’s Valley Urgent Care Center. Another four injuries were reported outside El Centro. Broken bones, sprains, cuts and some mild heart attacks were reported.
The woman reported killed in Mexicali was identified as Carmen Garcia Munoz. The child was not immediately identified.
Officials in the U.S. border town of Calexico said that a furniture store’s brick wall collapsed on several automobiles and there was damage to other buildings in the downtown area. Part of a brick wall collapsed on a car belonging to a waitress who had just shown up for her job at an El Centro cafe.
Outside Calexico, mobile home dweller George Jenkins said that when the quake struck, his trailer “started rolling like a baby’s cradle. . . . My dogs were barking outside. I woke up my wife and we ran.”
Westmorland, population about 1,500, was the town nearest the epicenter.
“This one this morning was the freakiest I’ve ever been in,” said Westmorland resident Donna Ginnis. ". . . My whole bedroom was spinning. The quake knocked our bedroom door to the floor. My little boy was petrified.”
An official in Mexicali said that 650 people were evacuated from 35 buildings that appeared to have suffered structural damage. This included about 200 from the 9-year-old municipal hospital, and others from two other hospitals and the badly damaged City Hall. The Mexican army was called in to provide security and schools were closed for the day. A flower shop was destroyed by fire.
At the municipal hospital, Dr. Antonio Gomez Vera, the director, said: “We had several patients who became very anxious and hysterical, but we still evacuated the entire hospital in about 30 minutes. . . . Our biggest challenge right now is giving these people food and drink.”
Caltech seismologists said the main shock was on the Superstition Hills Fault northwest of the Imperial Valley and that a 4- to 7-inch horizontal displacement was found on Imler Road, southwest of Westmorland.
The Superstition Hills Fault is believed to be part of the San Jacinto Fault system.
Monday night’s 5:53 p.m. quake originally had been assessed at 6.2 on the Richter scale but was downgraded to 6.0 on further evaluation and reclassified as a foreshock Tuesday.
Centered about six miles northeast of the epicenter of the main shock, it occurred on a previously unrecognized fault that runs southwest to northeast under the southern edge of the Salton Sea and perpendicular to the Superstition Hills Fault.
Caltech seismologists called the two-day episode, which also was marked by 5.4 and 5.5 shocks as well as more than 30 above 3.5, the Superstition Hills sequence. Seismologist Kate Hutton said it was a “very rich aftershock sequence” and cautioned, “They’ll be feeling shocks for weeks out there.”
There were “literally thousands” of aftershocks above magnitude 2, Hutton added.
Hutton noted that the geological forces that powered the quake are the same ones that pulled Baja California away from Mexico to form the Gulf of California.
Tuesday’s quake caused numerous power and telephone outages and gas line breaks in an area extending from Westmorland through El Centro and Calexico into Mexicali.
Authorities estimated that 65,000 households and business lost power after the early morning shock, but 95% of the outage was corrected within 20 minutes, according to a spokesman for the Imperial Valley Water District.
State emergency authorities also said there had been some cave-ins along the All-American Canal, which carries irrigation water from the Colorado River into the farmlands of Imperial Valley, although there were no reports that the flow of water was disrupted.
Bulldozers were dispatched to repair the damage.
A number of trailers fell off their foundations and there was substantial window breakage and grocery damage in the valley. Many stores closed temporarily to pick up merchandise and sweep aside broken glass.
A spokesman at the U.S. Naval Air Facility seven miles west of El Centro said there were “a couple of hairline cracks across our runway” and some damage to photographic and electronic equipment at a nearby bombing range. But, he added, it had no effect on operations.
A main Imperial Valley highway, California 86, was closed between Westmorland and El Centro because of damage, and California 98, paralleling the Mexican border, was closed at Ocotillo after the road buckled on an overpass at the junction of that highway and Interstate 8.
Authorities at the border crossing between Mexicali and Calexico ordered the U.S. entry station closed until a survey could be made of extensive damage inside the building.
“It just popped the whole building,” Immigration and Naturalization Service Supervisor Windle Roach said of the earthquake. “There was, bang, a whomp, and it startled everyone. The building was immediately cleared out. We’re not answering phones and we’re not going in until they tell us it’s safe.”
In downtown Calexico, which is on the U.S. side of the border, police headquarters called in its entire force to prevent looting. “We had a couple of people who tried to loot merchandise,” said officer B. Ramos. But, he said, they didn’t get away with anything.
U.S. Customs Service planes and Mexican aircraft flew over the Calexico-Mexicali area surveying the damage.
At Gio’s Mobile Home Park in El Centro, where between 10 and 15 double-wide trailers shifted from their foundations, resident Joe Bishop, sitting on his porch, was thankful that his home had escaped damage.
“I’ve got a one-word vocabulary: lucky,” said Bishop. “As hard as things were moving and as violently as it was shaking, I was really surprised that a lot more stuff didn’t come out of the cupboards. I have no idea why it didn’t.”
At the Immigration and Naturalization Service detention center in El Centro, inmates were moved into the courtyard until it was determined that the structure was safe.
A state Health Department spokeman, Bob Borzelleri, said that the International Technology Corp. had reported that the office and laboratory of its toxic waste facility in Westmorland had been knocked from its foundation. He said there was no indication of damage to the waste ponds and no imminent hazard to health, but that the Health Department would send a geologist to inspect the facility.
In Orange County, there was no reported damage from the temblor, said Pete Lawrence, a spokesman for the Emergency Management Division of the Orange County Fire Department which monitors earthquakes and coordinates responses to them in the county.
In La Habra, which was the community hardest hit in Orange County by the October quake, the city’s Building Department received calls Tuesday from four homeowners wanting their houses inspected, said Tom Lynn, one of the department’s four inspectors.
“But we haven’t had a chance to get out there, so we don’t know if the damage was caused by the quake this morning--or if people just got scarred by the jolt and wanted us to look at damage that had been done in October,” Lynn said.
Maintenance crews in Orange County for the California Department of Transportation reported to work an hour early Tuesday to begin inspection of freeway bridges. At 6 a.m. the 150 men belonging to 16 different work crews fanned out throughout the county, said George Hays manager for Caltrans in Orange County.
By noon the crews had completed their visual inspection of “several hundred” bridges for cracks and other damage from the temblor, Hays said. “They all checked out OK,” Hays said. “We had no problems with the freeways.”
The quake prompted some Orange County residents to buy earthquake survival supplies. The Army-Navy Store in Orange reported a brisk business in water bottles, water purification tablets and propane tanks.
“We had about two dozen people come in (Monday) night, and another 40 come in today,” said Eraina Taylor, a clerk at the Army-Navy Store. “Most of them already had their earthquake preparedness kits together, and they just needed a couple of things to finish them out.”
Many young children in Orange County were left jittery by the quake, so their teachers had open discussions with them about what to do in earthquakes, said Tim Harvey, disaster coordinator for the Brea-Olinda Unified School District and principal of Fanning Elementary School in Brea.
“Children are worried that this quake, or the next one, might be the Big One, so they want to talk through any anxiety they might have about being ready,” Harvey said.
In Los Angeles, some residents reported being awakened by Tuesday’s quake, but no damage was reported.
It was felt more strongly in the Palm Springs and San Diego areas.
In San Diego, the Fire Department reported that five of its stations developed minor cracks in walls and ceilings. The San Diego Gas & Electric Co. said an electrical power line was downed at a downtown intersection but there were no service disruptions.
Gov. George Deukmejian, in New Mexico for a Republican governor’s conference, ordered the state Office of Emergency Services to convene a federal-state damage assessment team. The team was reported already at work by the end of the day.
The Imperial Valley has historically been one of the most seismically active areas of the state. There have been quakes of magnitude 6 or higher in 1915, 1940 and 1979, with the strongest, a 7.1 quake that killed seven people, occurring in 1940.
H. G. Reza reported from Imperial County and Mexicali and Kenneth Reich from Los Angeles. Also contributing to this story were Times staff writers Ted Rohrlich in El Centro, Thomas H. Maugh II in Pasadena, Armando Acuna in San Diego and researcher Tracy Thomas in Los Angeles.