5.2 Quake Hits Southern California
2004 06 17
 The largest earthquake felt in San Diego in nearly two decades struck off the coast of Baja California yesterday. There were no reports of injuries or significant damage.
The magnitude 5.2 quake, experienced as a sharp jolt in some areas, hit just before 3:29 p.m., causing high rises in downtown San Diego to sway.
The epicenter was 49 miles southwest of San Diego, the U.S. Geological Survey reported.
The quake could generate aftershocks for several weeks. Most will be too small to be felt, but the most powerful could reach about magnitude 4.0, said Frank Vernon, a geophysicist at UCSD's Scripps Institution of Oceanography in La Jolla.
Seismologists described the quake as "moderate," but it was nevertheless the most powerful one felt in California since a magnitude-6.5 quake near Cambria on Dec. 22 killed two people, injured 40 and caused up to $250 million in damage.
It also was the largest quake to rock the San Diego region since 1986, when a swarm of quakes topping magnitude 5.4 struck off the coast of Oceanside.
Yesterday's quake occurred on or near the San Clemente fault, about four miles beneath the ocean floor, scientists said.
There was some initial confusion about the quake's origin. In the moments after the temblor, USGS computers incorrectly showed quakes near Lancaster in the Mojave Desert and Agoura Hills in northwestern Los Angeles County. There were no earthquakes yesterday in either place.
Offshore quakes can generate erroneous readings, but such computer errors are quickly corrected, said Susan Hough, a seismologist with the USGS in Pasadena.
Yesterday's quake was not the large earthquake forecast by UCLA professor Vladimir Keilis-Borok, who has predicted that such a quake will strike in the Southern California desert at some point before Sept. 5. Many seismologists are skeptical that earthquakes can be predicted at all.
Authorities on both sides of the border spent the hours after yesterday's quake checking for damage to bridges, structures, railroads, amusement park rides and even coastal bluffs. No damage was reported and soon the trains and roller coasters were moving again.
Officials in Tijuana evacuated City Hall and the state government building as a precaution, said Antonio Rosquillas, director of Tijuana's civil protection office.
Rosquillas said the quake served more as a reminder to residents of the shaky ground they live on.
"We are surrounded by faults," he said.
In San Diego, fire department crews hit the streets to check their neighborhoods for damage and found none, said spokesman Maurice Luque. Other fire and police agencies in the county also had no reports of damage.
Caltrans dispatched maintenance crews to check bridges and overpasses for any signs of damage. None was reported.
An inspection of the new Petco Park, where the San Diego Padres opened a nine-game homestand last night, also found no visible damage, a spokesman said.
SeaWorld operators quickly shut down the Mission Bay park's new, 95-foot-tall Journey to Atlantis coaster ride and evacuated 35 riders by stairway. After an inspection, the ride was back in operation by 5:45 p.m., said SeaWorld's Dave Koontz.
At the San Diego County Fair in Del Mar, workers briefly cleared 78 rides and checked utility lines after the quake, said Linda Zweig, fair spokeswoman. Rides at Legoland in Carlsbad also were shut down and evacuated as a precaution, said a spokeswoman. They, too, reopened after an inspection and testing.
The North County Transit District and Amtrak halted rail traffic north and south of the coastal bluffs in Del Mar while the track was inspected and found to be undamaged.
At Torrey Pines State Beach, lifeguard Jeff Bruck said he was advising a nude couple about the risks of sitting too close to the cliffs when he "felt the earth shake and saw sand sliding down the face of the cliffs," Bruck said. "I told them I thought it was a good idea to move away from the bluffs. They agreed."
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