Gene Dorio: Predicting the future from the past

Dr. Gene Dorio

Mother Nature is unpredictable, and the disaster in Montecito begs the question could some of it have been prevented? Recent fires denuded the area allowing loose unrooted soil to be washed downhill toward the ocean. Would calculations from anticipated rainfall have helped prepare for mudslides and floods in runoff areas?

Many natural and man-made disasters have affected the Santa Clarita Valley, so I would like to connect some from the past to prepare for the future.

On March 12, 1928, a dam built 10 miles north of Santa Clarita in San Francisquito Canyon ruptured killing over 400 residents along its wake to the Pacific Ocean. The St. Francis Dam catastrophe was an engineering disaster which most felt could have been prevented.

On February 9, 1971, Sylmar suffered a 6.6 earthquake. The nearby Van Norman Reservoir threatened to rupture. Twenty miles to the north along Interstate 5 is Castaic Dam. Scientists feel it is earthquake safe up to 8.0.

With this information and background in place, I want to point out several important facts:

– Castaic Dam is 30 miles south of the San Andreas Fault; with two minor faults much closer, Holser and San Gabriel;

– The Van Norman Reservoir is “earth-fill” compacted with soil, sand, clay, and rock. So is Castaic Dam;

– Water volume in Castaic Dam is 8.5 times the amount that was contained in the St. Francis Dam;

– The tidal wave from a rupture in Castaic Dam would follow Castaic Creek south until it intersects with the Santa Clara River at Highway 126, then flow west to the ocean just like it did with the St. Francis Dam disaster;

– Debris, including boulders, trees, and mud, cause most fatalities as those swept into the current receive trauma, then drown;

– Many homes, roads, developments, and businesses are now along this tsunami path as estimated population growth in this area is almost 100 times since the 1928 St. Francis Dam disaster;

– Only about 4,000 people resided in the Santa Clarita Valley in 1940, and the estimate for 2040 is 400,000. About 10% of the population drowned in 1928, so now a greater water volume and population puts more people at risk if Castaic Dam ruptures.

What is the chance of a > 8.0 earthquake…”The Big One”? Could it will be in the area of Castaic Dam? Can we be prepared in the event this occurs to assure our safety?

I am not an engineer or a water scientist, but I would like to make recommendations that these experts might consider:

– Calculate the flow pattern, speed, elevation, and all potential directions a flood might follow as it traverses to the Pacific Ocean;

– Establish a warning system (better than in Hawaii) the public will recognize day or night if the dam ruptures;

– Make sure all vehicles on roads and highways have an escape route immediately delineated;

– If the dam ruptures, make sure there is elevated strategic locations that can be run or driven to;

– Assure all schools know where higher ground is, and can be accessed;

– Have water engineers determine if breaker walls and water diversions can be created to better direct the flow toward the ocean and away from populated areas, and sweep the area of potential debris;

– Determine if there are safety and evacuation models to follow in other earthquake prone areas (like Japan) where dams and reservoirs exist.

I am certain the public can contribute more recommendations.

The Santa Clarita Valley should be aware of this threat, and voice their concerns.

Lessons learned from the past might help to predict and avoid another Montecito disaster, while saving lives and heartache in the future.

Gene Uzawa Dorio, M.D., is a Saugus resident.

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