A magnitude 3.5 earthquake rattled parts of the Los Angeles area early Friday.
The quake, initially calculated as magnitude 3.7, hit at 12:19 a.m. and its epicenter was near the intersection of Compton Boulevard and Alameda Street in Compton. According to the U.S. Geological Survey, the temblor was felt from Orange County to the San Fernando Valley and Malibu.
The USGS calculated that light shaking was felt in Compton, Lynwood, Gardena, Willowbrook, Lakewood and northern Long Beach. Weaker shaking was likely felt throughout the Los Angeles Basin and the San Gabriel Valley. Homes in Burbank and Rowland Heights shuddered; in El Segundo, one person felt a strong jolt intense enough to be woken up.
The quake had an epicenter about two miles from a mapped strand of the Newport-Inglewood fault, which was responsible for the deadly 1933 Long Beach earthquake. That earthquake, estimated to be magnitude 6.4, caused 120 deaths, including 52 in Long Beach and 17 in Compton.
The Newport-Inglewood fault is considered particularly dangerous because it runs directly underneath so many cities in Southern California, from the Westside of Los Angeles through Beverly Hills and Long Beach to the Orange County coast. It’s believed to be connected with the Rose Canyon fault system that continues into San Diego.
A study in 2017 found that major earthquakes on the fault centuries ago were so violent that they caused a section of Seal Beach near the Orange County coast to fall 1½ to 3 feet in a matter of seconds.The observations from that study suggest that earthquakes as large as magnitude 6.8 to 7.5 have struck the Newport-Inglewood/Rose Canyon fault system.
Seismologist Lucy Jones said on Twitter that the quake was near but not directly on that fault.
Jones said the quake was quite deep — about 15 miles under the ground surface; most quakes in the L.A. Basin are about 9 miles deep.
Generally speaking, relatively deeper quakes are felt less intensely at the surface. But they can be felt over a broader area.
The M3.7 in Compton is near but not on the Newport-Inglewood fault. It was also very deep (15 miles) so no one was really close to it. Very similar to a M4.0 Oct. 28, 2001 which was ~1 mile northwest and just about as deep.— Dr. Lucy Jones (@DrLucyJones) October 18, 2019
Compton M3.7: Why so deep? Most quakes in LA basin are in the top 15 km. This quake was at 24 km and we have seen others that deep before. This is at the boundary between the part of the crust that is brittle (can break in quakes) and the hotter, ductile rocks that bend. 1/— Dr. Lucy Jones (@DrLucyJones) October 18, 2019
Compton M3.7: Deep quakes start in the good transmitting rocks and only has to pass through the absorbing rocks once. So they are felt farther away— Dr. Lucy Jones (@DrLucyJones) October 18, 2019
The intensity of Friday’s quake is not enough for significant structural damage to be expected.
The magnitude of the earthquake is too low for it to activate computer systems that would push out an earthquake early warning alert through the ShakeAlertLA or MyShake apps, which require a minimum earthquake magnitude of 4.5. There was one aftershock.
The initial earthquake occurred less than a mile from Willowbrook and East Rancho Dominguez, and one mile from Lynwood and Long Beach.
In the last 10 days, there have been no earthquakes of magnitude 3.0 or greater centered nearby.