Quake Rolls Through Borrego


Last updated 7/30/2019 at 11:14pm

Aside from Fourth of July celebrations and enjoyment, Southern California was in for quite the shock, after two large earthquakes shook the lower-east Central Californian region of Ridgecrest. The rock was felt in parts of Southern California and Nevada, as far as Los Angeles and Las Vegas.

The first quake on July 4, a magnitude-6 on the new seismic scale, not really felt in Borrego, probably because it was 1/10th as powerful as the second one, the next day, with a magnitude-7.1, one of the most powerful quakes in California history. They both fell into the Large Earthquake range.

With its remote location, it made it far less destructive and deadly than smaller quakes whose epicenters were in urban areas.

Within Borrego, the gentle rolling effects were apparent if you were not active at the time. The mere thought of that much land mass in motion, seismic waves rippling over the entire California landscape, gives one pause to reflect on preparedness for “The Big One.”

California Institute of Technology seismologist Lucy Jones said since officials began measuring earthquakes in 1932, there have been 22 of a magnitude-6 and above. Only two of those – including the one on July 4 – have been a foreshock to a larger one.

The last was in 1987, when a 6.2-magnitude quake struck south of the Salton Sea, followed by a 6.6 quake 12 hours later.

A magnitude-6.5-7.5 seismic event in Borrego will be a challenge to deal with for first-responders and residents alike, but it’s going to happen. We just don’t know when.

Quake preparations can range from the simple – having earthquake kits and emergency plans ready – to more expensive items like backup generators and quake insurance, and retrofitting buildings to better withstand shaking.

The two recent quakes in Ridgecrest took down unreinforced chimneys (unreinforced is the most common), ripped roads apart, and caused a lot of shaking and rattling, including local nerves from Ridgecrest residents.

There were no reports of injuries to those who felt the shaking in Borrego Springs. However, many residents have had cracks in their foundation or concrete.

There have been about 3,000 aftershocks, many below the level of human detection (M1-M3).

Several years ago, the Sun published a series on the San Jacinto Fault Zone, the most active in California.

It may be time to revisit that series and extract info on the nature of earthquakes and Borrego’s preparedness status for The Big One.

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