Moderate Quakes Rock Southern California, Damage Minor
LOS ANGELES (AP) _ Two earthquakes a half-hour apart shook Southern California on Monday, knocking items off shelves, cracking the plaster in City Hall, disrupting phone service and prompting workers to evacuate offices.
There were no reports of serious damage or injuries.
A quake measuring 4.5 on the Richter scale struck at 9:57 a.m. and was followed by a 4.3-magnitude aftershock at 10:25. The quakes were on the same fault as the Whittier Narrows quake and its aftershock that killed eight people in 1987.
″It was like a ride at Magic Mountain where it just shakes and shakes,″ said Joseph Libby in Torrance, about 15 miles south of downtown Los Angeles. ″Some things fell off shelves, like books, but I can’t see any real damage.″
Their epicenter was about 10 miles southeast of downtown in Montebello, said Kate Hutton, a seismologist at California Institute of Technology.
The quakes, which were felt as far east as Banning, 85 miles from downtown, temporarily knocked out the Caltech seismology lab’s hotline to the California Department of Emergency Services as well as other phone lines, Hutton said.
The quake was classified as moderate, but because it was centered in the densely populated Los Angeles basin it rattled millions of people.
The tremor shook City Hall violently for 12 to 15 seconds, knocking plaster down. At the nearby Hall of Administration, many of those attending a Board of Supervisors meeting scurried into the streets as the jolts sprinkled the room with plaster. Guards ordered everyone out of the room as a precaution.
Other downtown buildings also had cracked and falling plaster.
″It was like a bouncing feeling,″ said Mavis Lopez, a receptionist in a 51st-floor office in the Wells Fargo building. ″I saw people running out of their offices, but everybody knew what it was and they were relatively calm.″
At the first jolt, Los Angeles fire trucks pulled out of their garages and went out patrolling neighborhoods for damage, said spokesman Greg Acevedo. ″Our helicopters are in the air to check for damage at the reserviors,″ he said.
No significant damage was reported in checks with police and sheriff’s stations and firehouses.
″Los Angeles building codes are such that 4.5′s should not cause any serious damage,″ Hutton said.
The Richter scale is a gauge of the energy released by an earthquake as measured by the ground motion recorded on a seismograph. Every increase of one number means a tenfold increase in magnitude.
An earthquake of 3.5 can cause slight damage, 4 moderate damage, 5 considerable damage, 6 severe damage. A 7 reading is a ″major″ earthquake, capable of widespread heavy damage; 8 is a ″great″ quake, capable of tremendous damage.
The San Francisco earthquake of 1906, which occurred before the Richter scale was devised, has been estimated at 8.3.
Monday’s earthquakes were about six miles west of Whittier, where a 5.9- magnitude quake struck Oct. 1, 1987, and a 5.3 aftershock Oct. 4 caused $358 million in damage, eight deaths and 200 injuries.