Last summer, a scientist from the Scripps Institution of Oceanography warned that the southern San Andreas fault is poised to explode, leaving the Los Angeles area at risk for a devastating earthquake.
Because the southern end of the San Andreas fault near Los Angeles has been dormant for more than two centuries, scientist Yuri Fialko said it is under immense stress and could produce a massive earthquake at any moment.
Fialko said that, considering average annual movement rates in other areas of the fault, there could be enough pent-up energy in the southern end to trigger a cataclysmic jolt of up to 32 feet. A movement of that magnitude would be among the largest ever recorded.
According to the U.S. Geological Survey, the earthquake that destroyed San Francisco in 1906 was produced by a sudden movement of the northern end of the fault of up to 21 feet. The USGS says the most recent major earthquakes in the northern and central zones of the San Andreas fault were in 1857 and 1906.
Fialko said there had been no recorded movement at the southern end of the 800-mile-long fault since the dawn of European settlement in the area, and this lack of movement could spell trouble. The longer the fault goes without movement, the larger the eventual quake will be, and the more certain that eventual movement becomes. Geological evidence points to major earthquakes at the southern end of the fault of every 200 to 300 years. The last recored quake along the Southern San Andreas was 250 years ago, putting Southern California smack dab in the middle of the current cycle.
According to Fialko’s observations, stress rates indicate that the southern section of the San Andreas fault may be “approaching the end of the interseismic phase of the earthquake cycle.” Lending gravity to Fialko’s prediction, all of his calculations are based on a wide range of land and satellite observations.
The San Andreas is the geological meeting point of the Pacific and the North American tectonic plates. Slippage rates of just centimeters a year can prevent the build-up of explosive pressure deep underground. But when certain areas become blocked and then suddenly break free, they produce tremors or earthquakes of varying intensity depending on previous movement and the duration of the blockage.
Fialko says that the longer the fault remains quiet, the greater the likelihood of a future “event.” And as he sees it, that event is an impending disaster for Southern California.
According to Fialko , all his observations “lend support to intermediate-term forecasts of a high probability of major earthquakes on the southern SAF system.”
But a large quake need not directly strike the Los Angeles area to have a devastating impact.
Scientists say there’s a 62% chance of a massive quake, magnitude 6.7 or greater, striking the Bay Area before 2032. They’re particularly worried because everyone now knows what a $100 billion disaster looks like — namely Katrina.
There were approximately 800,000 people living in the Bay Area when the 1906 quake struck, and more than 3,000 of them died. By contrast, there are about 7 million people living in that area today. Extrapolate the 1906 death rate, and the death toll could amount to 28,000 today. Furthermore, the region is home to a vibrant $350 billion economy that includes one of the nation’s biggest financial centers, one its busiest ports, and one of the world’s densest concentrations of technical and scientific talent.
Geologists and seismologists are concerned that if a big quake strikes San Francisco, the aging levee system would fail. The levees protect not just farmland and residential areas, but also the water supply for some 23 million people. If the levees crumble, a major concern of Gov. Schwarzenneger, the water from the Bay would surge inland covering parts of Oakland, and contaminate the freshwater aqueducts that carry water all the way to Los Angeles.
So a quake in the Bay Area would have devastating consequences for the entire state, including L.A. And if Katrina taught us anything, it’s that in the event of a major disaster, all citizens need to be able to fend for themselves and their families for days on end, until help finally arrives.