Three earthquakes have struck the Newport Beach and Costa Mesa areas of Southern California over the past two days, including two late Thursday afternoon.
The first earthquake struck along the border of Newport Beach and Costa Mesa at 4:52 p.m. Thursday. A 3.6-magnitude earthquake occurred near Irving Avenue and at the transition between Westcliff Avenue in Newport Beach and East 17th Street in Costa Mesa.
Then, at 5:04 p.m., a magnitude 3.4 aftershock struck, centered about three-fifths of a mile to the southeast, beneath the residential streets of Somerset Lane, a few blocks from Upper Newport Bay.
In addition to Newport Beach and Costa Mesa, weak tremors were felt in Santa Ana, Westminster, Huntington Beach, Garden Grove and Irvine, according to the U.S. Geological Survey. That is, the McCully strength level is corrected to level 3. This shaking creates a vibration similar to that of a passing truck and may shake more cars slightly.
The foreshock of Thursday’s earthquake occurred at 1:46 p.m. Thursday and was initially estimated to be a 2.6 magnitude epicenter beneath Mariners Park in Newport Beach. It was later upgraded to a 2.8 magnitude epicenter a quarter mile northwest to Kos. A residential area in Tamesa.
The three earthquakes occurred near mapped traces of the Newport-Inglewood/Rose Canyon fault zone. The Newport-Inglewood Fault has long been considered one of Southern California’s worst seismic hazards because it lies beneath some of the region’s most densely populated areas, from West Los Angeles to the Orange County coast.
The last major earthquake on this fault occurred in 1933, the magnitude 6.4 Long Beach earthquake. The 1933 earthquake killed nearly 120 people and caused $40 million in property damage.
There were several earthquakes in the area last week.
Earlier this week, two earthquakes struck the El Sereno area east of Los Angeles. The first, a magnitude 3.4, struck at 9:56 a.m. Sunday a few blocks south of Huntington Drive and Eastern Avenue.
The second earthquake, measuring 2.8 in magnitude, lower than the previous estimate of 3, occurred at 3:05 pm on Tuesday. The latest estimated epicenter was about 700 feet northwest of Sunday’s quake.
A magnitude 3.6 earthquake (down from the initial estimate of 3.8) struck at 10:26 a.m. Friday in the northern Ojai Valley, causing weak tremors from Santa Barbara to Los Angeles.
Small earthquakes are not uncommon in Southern California. Most do not result in larger, catastrophic earthquakes. Although some larger earthquakes are preceded by smaller earthquakes, this is not always the case.
Experts say it’s impossible to know whether a small earthquake is a foreshock of a larger one until a more powerful quake strikes.
