The possibility of a pandemic is understandably scary but the real thing the US must worry about is the perpetual threat of a very sudden, very violent earthquake along the section of the San Andreas Fault that hasn’t had any movement for over 100 years. The chaos and destruction this event can cause is obviously immense. This is due to California becoming rapidly overpopulated, considering that it is one of the more geologically active, dense populated places on earth, similar to Sichuan province in China or the Tokyo region of Japan. Over the course of the last year, we have watched the number of micro earthquakes and sub-5.0 events growing in number and intensity along and around both ends of the San Andreas Fault. This last 24 hours has seen a 3.5 quake very, very close to the center of the section of the San Andreas Fault. This point is pretty much the middle point of the section that hasn’t had a major quake since the early Gold Rush era.
The chances of a major event rises by the day. It isn’t a question of it ever happening: this is obvious, it will and must happen. The only question is, the actual time frame. Pinpointing earthquake events is extremely tricky. This is why we have to assume it can happen any time and take whatever possible preparations we can, to deal with this.
Here is a Google satellite map showing close up, where today’s quakes were located. Right next to the ocean. To the upper right corner, there is a hot springs. Throughout California, there are these hot springs which signal a potential tectonic stress point.
LENGTH: 1200 km
550 km south from Parkfield; 650km northward
NEARBY COMMUNITY: Parkfield, Frazier Park, Palmdale, Wrightwood, San Bernardino, Banning, Indio
LAST MAJOR RUPTURE: January 9, 1857 (Mojave segment); April 18, 1906 (Northern segment)
SLIP RATE: about 20 to 35 mm per year
INTERVAL BETWEEN MAJOR RUPTURES: average of about 140 years on the Mojave segment;recurrence interval varies greatly — from under 20 years (at Parkfield only) to over 300 years
PROBABLE MAGNITUDES: MW6.8 – 8.0
San Andreas Fault Zone — San Gorgonio Pass Area:
The San Gorgonio Pass area is fairly complex, geologically speaking. Here the San Andreas fault interacts with other faults (most notably the San Jacinto fault zone and the Pinto Mountain fault) and thereby becomes somewhat fractured, over the distance extending from just north of San Bernardino to just north of Indio, some 110 kilometers (70 miles). Because this deformation has been going on for well over a million years, ancient and inactive strands of the San Andreas fault can be found here. Other faults in this area are have been “reawakened” recently after being dormant for hundreds of thousands of years. There is even evidence to suggest that there is no active, continuous main trace of the San Andreas fault going all the way through the pass, not even at depth — implying that the San Andreas fault may currently be in the process of creating a new fault path through this area! This could also mean that a single, continuous rupture from Cajon Pass to the Salton Sea (a stretch of the San Andreas that has not ruptured in historical times) is unlikely to occur. Fault rupture mechanics are still not well understood, however, and the discontinuity could prove to have little effect on tempering a major earthquake on this southern stretch of the San Andreas fault zone.
This US Geological Survey map shows how the two biggest quakes today in California are related to each other. Neither is on an major fault. The major faults are obviously accumulating a tremendous amount of stress which is translated into shakes at nearby points. Let’s look closer at the smaller quake near Bakersfield:
Looking closer, we see this is near farmlands and is in the mountains. There are huge geological differences between the flat farmlands and the mountains associated with the San Andreas Fault.
Here is a satellite photo showing the San Andreas Fault and how it runs exactly parallel to the sandy desert strip on the other side of the twisted, tormented mountains that are on the eastern side of the San Andreas.
There are various guesses where this next mega earthquake event will begin. I want to point out some interesting features of the San Andreas. One is, the several hot springs that lie on or near the slip/strike zone. Below is a close up of a very interesting intrusion of some very complex geological features near San Bernandino. Notice the Arrowhead Springs Hot Lake location. Directly below it and obviously the path of most water flows, is where the San Andreas passes through some pretty conflicting geological masses.
Here is a super close-up where the red arrow is pointing. One of the more amazing features of the San Andreas Fault is how straight it is for much of its length.
Another hot springs is near where the San Andreas makes one of its few bends. This is where the Salton Sea depression begins. Of course, this fault can break nearly anywhere along its length. It can break in the middle and waves of energy move in opposite directions, it can break in one spot and move northwards, for example. The whole thing can go out, all at once or just a tiny fragment.
No one can tell which of these events will happen or when they will happen. One thing is certain, these things have an excellent fashion of being inevitable. So the sane thing to do, if one wishes to live in very active geological zones, is to be prepared. California is a ‘dry’ state in that one can’t expect water to always be there, it has to be transported, often over hundreds and hundreds of miles.
And nearly all of the transmission of water is across the San Andreas. And any disruption of any of these systems will have tremendous effects on the milling millions who live, totally dependent, on this water delivery system. The very most important thing all people in California must do, especially in the much drier southern half, is have lots and lots and lots of potable water stored somewhere safe and accessible.
- California’s communities, farms and businesses rely on water from a variety of sources. Surface water projects, which capture and deliver rain and snow runoff, provide a major portion of the state’s total water supply. The projects include more than 1,000 federal, state and local reservoirs and hundreds of miles of canals and pipelines.
- Two of the most important projects are the federal Central Valley Project (CVP) and the State Water Project (SWP). The CVP and SWP bring water from Northern California through the Sacramento-San Joaquin River Delta for delivery to users in the San Joaquin Valley, parts of the San Francisco Bay Area and Southern California.
- Key water projects and the amount of water they deliver:
- Central Valley Project (federal). Delivers about 7 million acre-feet (MAF) per year. Constructed in 1930s – 1950s.
- State Water Project (state). Delivers about 2.3 MAF / year. Constructed in 1960s – early 1970s.
- All-American Canal (local). Delivers 3 MAF / year. Constructed in 1930s.
- Colorado River Aqueduct (local). Delivers 1.2 MAF / year. Completed in 1941.
- Los Angeles Aqueduct (local). Delivers 200,000 AF / year. Completed in 1913.
- Mokelumne Aqueduct (local). Delivers 364,000 AF / year. Completed in 1929. Second aqueduct completed in 1949.
- San Francisco Hetch Hetchy Project (local). Delivers 330,000 AF / year. Completed in 1923.
Much of the population growth was in the dry, sunny southern half of the state, the part that needs water delivery the most. And it is the part most vulnerable to water delivery disasters if there is a mega earthquake event. Many of these canals are quite old. And some have failed in previous earthquakes. We know it takes time to fix these things, too. So having a water supply of more than two weeks is recommended. Below is an article from today’s news in California:
Running through an obscure strip of isolated Imperial County, the All-American Canal rarely gets the attention of the other ditches that have shaped Southern California.
The Los Angeles Aqueduct, which brings water from the Owens Valley; the Colorado River Aqueduct, which supplies coastal Southern California; and the California Aqueduct, which brings water from Northern California, are near major population areas.
The All-American Canal brings copious amounts of Colorado River water to turn 500,000 acres of desert into some of the most productive farmland in the world.
As California struggles with drought, the 82-mile channel could be key. So on Thursday, water officials gathered at the canal to celebrate what they called a rare example of cooperation in the often contentious arena of water politics.
“This event is a big deal,” said Karl Wirkus, deputy commissioner of the U.S. Bureau of Reclamation, whose motto is “Managing Water in the West.”
At a patch of desert 35 miles east of El Centro and barely 50 yards north of the metal fence that separates the United States and Mexico, officials of several sometimes warring water agencies came together to celebrate the nearly completed project to line 23 miles with concrete to prevent seepage. The section was considered the leakiest part of the earthen canal.
The project is part of an agreement under which the Imperial Irrigation District, the canal’s operator, grudgingly agreed to sell some of its mammoth share of the Colorado River to water-deprived San Diego County. The cost of the $300-million project was split between the state government and the San Diego County Water Authority.
We look at the sun shining, they are happy, the temperature is balmy…the sort of grim determination we in the far northeast feel is missing in Southern California. Up here, we know that winter will come. Those of us, like myself, who have to heat our homes with wood, spend the sunny, happy summer, grimly cutting up, chopping and stacking huge piles of firewood for the inevitable winter.
Frankly, I find living in this sort of situation rather stressful. But then, peopl
Thinking ahead, considering how to keep the firewood dry during the summer and also, accessible if we have a tremendous amount of snow, is life and death. But since this process is annual, we find it pretty easy to shoulder the burdens and do all the preparations for winter. But preparing for a once-every 100 years event is trickier. People feel foolish if they store lots of water and worry about things.
For example, when I lived in California, I would sometimes go through really slow traffic snarls just so I could avoid the McArthur double decker section of highway in Oakland, California. I drove on it exactly once and announced, ‘This thing will collapse in an earthquake,’ and never used it again. It didn’t collapse while I was living there. It happened 10 years after I left. But it happened and this is the difference between our weather wariness here in the north and the lack of wariness in California: we have a calendar to rely on that goes by the month and day.
In California, they must rely on the geological calender which is set by hundreds or thousands of years. So, it is easier to ignore but much more dangerous, when it happens.