A 5.2-magnitude earthquake jolted Lamont, California, on Tuesday night and rumbled through a broad stretch of Southern California, Los Angeles Times reported, quoting the US Geological Survey.
The quake’s epicenter hit about 15 miles southwest of Lamont around 9:09 p.m. PT, but it produced no serious harm or casualties, the same source pointed out.
The California Highway Patrol said that two minutes after the earthquake, a big boulder the size of an SUV blocked numerous southbound lanes of Interstate 5, about a mile south of Grapevine Road.
The boulder was cleared by Wednesday morning. According to the United States Geological Survey, the earthquake struck around 9:09 p.m. and was originally estimated to be of magnitude 5.3.
It was followed by dozens of aftershocks of magnitude 2.5 and higher, including a magnitude 4.5 earthquake less than a minute after the initial and a magnitude 4.1 quake at 9:17 p.m.
The epicenter was in thinly populated farmland, approximately 14 miles northwest of the unincorporated settlement of Grapevine in Kern County, 60 miles northwest of Santa Clarita, and 88 miles northwest of downtown Los Angeles.
The area nearest to the epicenter experienced “very strong” shaking, as defined by the Modified Mercalli Intensity Scale; this zone includes a piece of the California Aqueduct, which delivers water from Northern to Southern California.
Some residents affected by the earthquake reported prolonged shaking. One witness in Los Feliz described 45 seconds of movement, with at least three distinct waves – one weak, followed by a powerful one, and then another weak one.
People in South Pasadena and Whittier reported feeling around 20 seconds of shaking in two distinct waves.
Geophysics professor Allen Husker, head of Caltech’s Southern California Seismic Network, said it was not surprising that so many people in the Los Angeles area felt strong shaking from the earthquake north of the Grapevine.
The temblor struck at night, when people are more likely to feel shaken by a distant quake than if they were out and about during the day.
Many people reported significant movement because of the way shaking is amplified in the Los Angeles Basin.
The basin is a 6-mile-deep, bathtub-shaped crater in the underlying bedrock filled with weak sand and gravel scraped from the mountains to generate the flat terrain that now houses millions of people.