One of the first questions you’re likely to be asked Wednesday will be “did you feel it?” — a magnitude-4.4 earthquake that struck north of La Verne. The earthquake struck at 7:33 p.m. Tuesday about three miles north of La Verne at a depth of 3.7 miles, according to the U.S. Geological Survey.
It 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.
A resident in Lakewood reported a “real sharp and fast” shaking.
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 in Los Angeles or La Verne, police in both cities said.
A Los Angeles County Fire Department dispatch supervisor said the department had received no reports of damage or injuries.
A check of Los Angeles County Sheriff’s Department critical facilities showed no signs of damage, authorities said.
No damage or injuries were reported in Pasadena, police there said.
Police and fire departments dispatched personnel to check for damage.
Seismologist Lucy 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.
California’s nascent earthquake early-warning system had another successful run Tuesday night in response to the shaker, the Los Angeles Times reported Wednesday morning. 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.
It 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 Wednesday’s 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 under development for years by the USGS, the nation’s lead earthquake monitoring agency, but the project has remained short of funds.
It’s 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.