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 Volume 12, Issue 16  |  February 25, 2020


Dennis’ Tidbits

By DENNIS McTIGHE 

February 11, 2020

Shake, rattle, and roll 

Dennis 5My latest column is actually being prepared on Sunday, Feb 9 because on this date in 1971 at 6 a.m., most of Southern California was jolted out of bed by a powerful 6.6 earthquake with its epicenter under Sylmar, Calif. It is situated near the foot of the San Gabriel Mountains in the San Fernando Valley. The quake was fairly shallow at about 12 miles, so the shaking was pretty violent and felt over a large expanse of land, from Santa Barbara to San Diego. 

Sixty-six people lost their lives, and there was extensive damage to hundreds of structures. The quake was the strongest in Southern California since July 10, 1952 when there was a powerful 7.7 that struck on the Inyo Kern fault on the way to Bakersfield. 

The summer of 1952 was a busy one for McWeather. I witnessed my first heavy thunderstorm that summer in the Grand Canyon, felt my first earthquake that July, and stood up on my first canvas surf mat at Main Beach. All of this at five years young!

Just off the top of my head – notable California earthquakes of 6.0 or greater magnitude: 1857, an 8.1 on the Christianitos Fault, which connects to the San Jacinto Fault, which connects with the San Andreas Fault. The quake leveled all of the missions in San Juan Capistrano. There was an 8.0 on April 10, 1906 in San Francisco as the San Andreas severely ruptured. On March 10, 1933 at around 6 p.m., a 6.4 struck near Long Beach. The epicenter was actually right under the power plant on Newland Street in Huntington Beach. 

In July of 1952, there was the 7.7 up by Bakersfield. Then of course, the 6.6 shaker in Sylmar on February 9, 1971. In May of 1983, there was a 6.7 near Hollister, north of Santa Barbara. On July 9, 1986, there was the 6.0 at 2:24 a.m. at Windy Point, outside of Palm Springs. 

On October 5, 1987, there was a 6.0 near Whittier Narrows about 50 miles up the road. On October 17, 1989, a 6.9 hit near Santa Cruz on the Loma Prieta Fault as San Francisco took a real beating. On June 28, 1992 at 5 a.m., a 7.5 hit near Landers way out there in the desert. It was more of a rolling motion as the quake occurred deep at 60 miles. Three hours later at 8 a.m., a 6.6 hit Big Bear. On January 17, 1994 at 4:30 a.m., there was a 6.8 in Northridge, and finally there was a 6.4 and a 7.1 last September near Ridgecrest.

More weather terms:

Halo: A prismatically colored or whitish circle or arcs of a circle with the sun or the moon at its center; coloration, if not white, is from red inside to blue outside (opposite to that of a corona); fixed in size with an angular diameter of 22 degrees (common) or 46 degrees (rare). I’ve only seen both at the same time twice here in Laguna. Characteristic of clouds composed of ice crystals; valuable in differentiating between cirriform and forms of lower clouds.

Hydrometer: A device used for the water vapor content of the air, for measuring relative humidity. I have two of these in my weather arsenal.

Ice Crystals: A type of precipitation composed as unbranched crystals in the form of needles, columns, or plates; usually having a very slight downward motion, may fall from a cloudless sky. 

Intertropical Convergence Zone: The boundary zone between the trade wind system of the Northern and Southern Hemispheres. It is characterized in maritime climates by showery precipitation with cumulonimbus clouds sometimes extending to great heights. It is the zone where many tropical systems get their act together.

Isobar: A line of equal or constant barometric pressure.

More of this stuff on Friday, ALOHA!

 

Shaena Stabler is the Owner, Publisher & Editor.

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Alexis Amaradio, Barbara Diamond, Dennis McTighe, Diane Armitage, Lynette Brasfield, Marrie Stone, Maggi Henrikson, Samantha Washer, and Suzie Harrison are our writers and/or columnists. Scott Brashier is our photographer.

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