At 8:08pm, on Saturday night, two moderate earthquakes struck in the Anza-Borrego Desert. A 4.9 and 4.5 magnitude earthquake hit approximately 9 miles north northwest of Borrego Springs, California. Both earthquakes occurred just south of the Anza Gap and are related to San Jacinto Fault.
The first earthquake was a 4.9 magnitude quake which struck at 8:08pm.
The second earthquake was a 4.5 magnitude aftershock that struck at 8:09pm.
Because the earthquakes struck so close together, only 24 seconds separated the two seismic events, the USGS had trouble determining the exact magnitude, location, and whether they had one or two events recorded. Within the first hour, the magnitudes were revised multiple times and the sizes ranged from 4.4 to 4.9 in magnitude.
At the time of this posting, the official answer seems to be that two quakes occurred, a magnitude 4.9 and a 4.5.
The epicenter of both quakes were far from any major town. Anza and Borrego Springs were the closest towns to the epicenter, both small desert communities. The San Diego Union Tribune quoted a clerk at the Borrego Springs Resort as saying, "...the building’s glass shook but did not break, and the resort had no damage." No damage or injuries were expected elsewhere as well.
Despite the quake being considered small to moderate, it was widely felt strongly by many in Imperial, San Diego, Orange, and San Bernandino county areas, as well as by people in the Los Angeles city area. Additionally, felt reports were received from Tijuana, Tecate, and Mexicali, Mexico.
Some of the communities that turned in the most felt reports included Carlsbad, Ramona, La Quinta, Santee, Escondido, San Diego, Poway, Encinitas, Temecula, San Marcos, Fallbrook, Palm Desert, Murrieta, and Oceanside.
I personally felt this quake while I was at work in Carlsbad, California. I was in an office building at the time, ground floor, in a hallway when the earthquake struck. It felt like something hit the building. The entire building suddenly shook violently. I stopped what I was doing and looked down the hallway. I heard the shaking travel through the building from one side to the other, east to west. I knew immediately that it was an earthquake. However, after the initial jolt, I could not feel any shaking afterward and no apparent damage had been done.
The following recording was made back home while I was at work. I have set up an earthquake cam in an attempt to capture a quake on video. Unfortunately, there is no sound, but what you will see is at least three things move in the shot. (According to the clock in the video) At 8:07pm and 49 seconds, the p-wave hits, effecting the chimes and the pendulum. A 8:07pm and 59 seconds, the pendulum and the ball move, almost in unison. You have to watch for the ball closely, though. It's very subtle. For the remainder of the video, the chimes and pendulum shake until they eventually calm down.
[Magnitudes and locations are subject to change as the USGS continues to review the data.]
-Article written by Tim "Lance" Sherwood of Oceanside, Ca.
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