Orange County Jolted By Multiple Back-to-Back Earthquakes

Seismological device for measuring earthquakes. Seismological activity live on the sheet of measuring paper. Earthquake wave on graph paper. Human hand showing earthquake.

A pair of tremors were felt late Thursday afternoon, adding to the trio of earthquakes that have rattled the Newport Beach and Costa Mesa areas in the past two days.

At 4:52 p.m. on Thursday, the boundary between Newport Beach and Costa Mesa was the site of the first earthquake. The 3.6-magnitude quake hit the area of Irvine Avenue and the intersection of Westcliff Drive and East 17th Street in Newport Beach and Costa Mesa, respectively.

At 5:04 p.m., an aftershock of magnitude 3.4 was felt, with an epicenter around 0.5 miles to the southeast, under the Somerset Lane residential area, a little distance from Upper Newport Bay.

In addition to Newport Beach and Costa Mesa, the following locations were also reported to have felt weak shaking: Santa Ana, Westminster, Huntington Beach, Garden Grove, and Irvine. If the shaking causes vibrations like a truck driving by, more automobiles may be gently rocked to the side.

On Wednesday at 1:46 p.m., a precursor to Thursday’s tremors occurred. The earthquake, which had an initial magnitude of 2.6, upgraded to 2.8 and shifted its epicenter one-quarter of a mile to the northwest, near a residential area of Costa Mesa. Its original location was beneath Newport Beach’s Mariners Park.

Three separate earthquakes struck in close proximity to known fault lines in the Newport-Inglewood/Rose Canyon area. From the coast of Orange County to the Westside of Los Angeles, the Newport-Inglewood fault passes beneath some of the most densely populated regions of Southern California, earning it a reputation as one of the top seismic hazard zones in the area.

The 1933 Long Beach earthquake, which had a magnitude of 6.4, was the last big quake to hit the fault. Nearly 120 people lost their lives, and $40 million worth of property was damaged in the 1933 earthquake.

Mild tremors are typical in the Southern California region. The vast majority of earthquakes do not cause devastating tremors, and little tremors aren’t necessarily precursors of major quakes.

According to experts, it is difficult, if not impossible, to determine in advance whether a smaller earthquake is a precursor to a bigger one.