A 4.6 Magnitude Earthquake in Southern California has Seismologists Concerned

Written By: Eleanor Pratt

Southern California residents are no strangers to earthquakes. According to the United States Geological Survey: “Each year the southern California area has about 10,000 earthquakes. Most of them are so small that they are not felt.” A few hundred of these earthquakes are larger than a 3.0 magnitude, and about 20 a year have a greater magnitude than 4.0.

Because these earthquakes happen fairly often, many who live in southern California often see them more as nuisances than a dangerous environmental phenomenon. When asked how she felt about earthquakes, former long-time Los Angeles resident, Carreen Weston said: “When I lived in LA, I was never concerned about an earthquake unless it was bigger than a 5.0. Honestly, anything less than that never really mattered to me or my friends.”

This brings us to the issue of the 4.6 magnitude earthquake that occurred on Friday, Sept. 18, 2020. According to the U.S. Geological Survey, the earthquake hit around 11:40 p.m. near Los Angeles. While there were no injuries or damage reported, there were fears of possible aftershocks and experts warned residents to remain alert. According to the Los Angeles Times, the quake was felt as far south as San Diego. About ten miles from the epicenter, South Pasadena residents felt sharp shakes and jolts, but luckily the power remained on.

Many southern Californians were not overly concerned, even though the earthquake was one of the larger to hit the area this year according to the Los Angeles Times. In fact, some were not bothered at all because a moderate-sized earthquake pales in comparison to other traumatic events in 2020. Los Angeles resident and internet personality, Ryan Bergara, tweeted at 2:47 a.m. on Saturday morning: “Won’t lie, I legit looked up at the ceiling and giggled during that earthquake. This year has broken me.” Ron Simms, who has lived in Los Angeles his whole life, described the quake as, “not a big deal.” and that “Nothing even fell off the shelves.”  

Even if many Los Angeles residents were not that worried about the earthquake, seismologists warn that these events in certain areas could spell disaster. KPBS reports that the temblor of the recent quake was centered near the epicenter of the Whittier Narrows earthquake of 1987. Dr. Lucy Jones, a seismologist, explained on Twitter that the Whittier quake was much larger at a magnitude of 5.9. Furthermore, according to The Los Angeles Times, it caused about $350 million in damage and resulted in eight deaths. The area where these two quakes occurred has been having increased seismic activity for several years.

The Puente Hills thrust fault is to blame for these recent earthquakes and the majority of earthquakes in Los Angeles and southern California in general. It stretches about 15 miles from downtown Los Angeles to the San Gabriel Valley. This fault worries seismologists because it runs under downtown Los Angeles, which is where the majority of the city’s skyscrapers are located.

The Los Angeles Times reports that, if a magnitude 7.5 earthquake or larger were to happen on the fault, it would do more damage than the much feared “Big One” along the San Andreas fault. The United States Geological Survey believes that if this 7.5+ earthquake happened along the fault, anywhere from 3,000 to 18,000 people could die, and there would be about $250 billion in damage.

Experts are taking this activity on the fault very seriously and are constantly monitoring earthquakes in the area closely to make sure they are prepared in the event that a major earthquake occurs along the fault. Due to the fact that most Californians live within 30 miles of an active risk fault line, according to California Earthquake Authority, California residents are advised to always have their emergency preparedness kit nearby and a plan in case of a larger earthquake.  

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