A magnitude 2.8 earthquake jolted the Los Angeles area Monday morning, sending weak shaking from its epicenter in Alhambra.
“Weak” shaking, as defined by the Modified Mercalli Intensity Scale, may have been felt in places such as downtown Los Angeles, Burbank, Pasadena, East L.A., South L.A., Beverly Hills and Universal City.
In Highland Park, there was a gentle rocking that lasted for about three seconds, similar to when a large truck drives by a home or when a helicopter circles a neighborhood. But in other places, like Glendale, the shaking was so subtle some people didn’t initially feel it as an earthquake.
The preliminary epicenter of Monday’s earthquake, recorded at 10:04 a.m., was near the corner of Valley Boulevard and Grand View Drive in Alhambra, just a few blocks from the northern terminus of the 710 Freeway and a few blocks east of the city limits of Los Angeles.
There have been a notable number of felt earthquakes in this area of Los Angeles County since summer, centered in El Sereno, a neighborhood of Los Angeles just west of Alhambra.
On June 2, a magnitude 3.4 earthquake was felt widely across Los Angeles and the San Gabriel and San Fernando valleys. Then, in almost the exact same location, a magnitude 4.4 earthquake hit on Aug. 12. That earthquake was felt far more widely across the Southern California region.
The magnitude 4.4 earthquake on Aug. 12 was centered within one of the region’s most potentially destructive fault systems, one capable of producing a magnitude 7.5 earthquake under the heart of the region.
A Times investigation published in November found that several suburbs in this general area of Monday’s earthquake have no active plans to require retrofits for seismically flimsy “soft-story” apartment buildings, despite the number of earthquakes felt in recent months.
The term applies to apartment buildings built decades ago where the bottom floor has room for a carport, garage or retail shop. In these buildings, the ground floor can be held up by flimsy, skinny poles that can collapse when shaken side-to-side in an earthquake.
Officials in Alhambra, with a population of around 82,000; and Monterey Park, where about 60,000 people live, said earlier this year their cities haven’t imposed mandatory retrofit ordinances for soft-story apartment buildings. Officials there said they’re closely monitoring neighboring cities and evaluating whether similar measures might be necessary.
In South Pasadena, with a population of 26,000, building officials said earlier this year the city has no plans to create an inventory of soft-story apartment buildings or consider mandatory retrofits.
Several years ago, there were plans to create an inventory of seismically vulnerable apartment buildings in South Pasadena, but city officials eventually determined it couldn’t devote the necessary resources, so plans to do so were scrapped.
More than a half-dozen cities in Southern California require soft-story apartment buildings to be retrofitted — Los Angeles, Torrance, Pasadena, Santa Monica, Culver City, West Hollywood and Beverly Hills. Burbank just passed a seismic retrofit law for soft-story apartment buildings last week.
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