Independent Staff and Wire Reports
LOS ANGELES — A magnitude-4.4 earthquake that struck north of La Verne Aug. 28 was felt at police headquarters in downtown Los Angeles and in Glendale, Lakewood, other parts of Los Angeles County and Orange, Riverside, San Bernardino, Kern and San Diego counties.
It also gave the state’s earthquake early-warning system another successful run. Seismologist Lucy Jones told reporters that the system sent out a warning three seconds before the shaking began.
The earthquake early-warning system is under development by the U.S. Geological Survey and is only available to a limited array of testers, but it is expected that more people will be eligible to test the system later this year, The Times reported.
The early-warning system works on a simple principle: The shaking from an earthquake travels at the speed of sound through rock, which is slower than the speed of modern communications systems. For example, it would take more than a minute for a magnitude 7.8 earthquake that starts at the Salton Sea and travels up the state’s longest fault, the San Andreas, to shake Los Angeles, 150 miles away. An early-warning system would give L.A. residents crucial seconds, and perhaps even more than a minute, to prepare.
A seismic early-warning system for the West Coast has been underdevelopment for years by the USGS, the nation’s lead earthquake monitoring agency, but the project has remained short of funds.
It is estimated that building a full system covering the West Coast would cost at least $38.2 million, with about $16.1 million annually to operate and maintain it, The Times reported.
The USGS has said it planned to begin issuing limited public alerts from the system by the end of this year, as long as funding wasn’t cut.
Southern California is one area where the network of seismic sensors is dense enough at present to begin early warnings.
For the system to go live all along the West Coast, more sensors need to be installed in Washington, Oregon and sparsely populated areas of Northern California, The Times reported. More than 850 earthquake-sensing stations are online, but about 800 more are needed, officials said. Too few sensors could mean, for instance, that Los Angeles would experience delays in warnings from an earthquake that starts in Monterey County and barrels south along the San Andreas fault.
Along the West Coast, facilities including airports, oil refineries, pipelines, schools, universities, city halls and libraries are already testing or planning to test the system, according to The Times.
The Aug. 28 earthquake struck at 7:33 p.m. about three miles north of La Verne at a depth of 3.7 miles, according to the U.S. Geological Survey. The USGS reported that a second quake, with a magnitude of 3.4, struck near the same area about a minute after the first.
There were no reports of damage.
Jones said the quake should not be expected to have done damage to structures.
Jones said the quake, felt as far away as Bakersfield and Oceanside, was not on the Sierra Madre fault, one of the largest in the region, but on an ancillary structure.
The earthquake was the largest in Southern California since Dec. 29, 2015, when a magnitude-4.3 quake struck near Devore, in San Bernardino County, Jones said.
A 5.1-magnitude earthquake struck in La Habra on March 28, 2014.
“This is a very ordinary earthquake for California, the size that we have several times a year somewhere in the state,” Jones said.
More than a dozen small aftershocks were felt and as is always the case, there was about a 5 percent the largest magnitude-4.4 earthquake would be followed by a bigger one, Jones said.
Jones retired from the USGS in March 2016 after 33 years to found the Dr. Lucy Jones Center for Science and Society to foster the understanding and application of scientific information in the creation of more resilient communities.