The big one is coming?


Fault Line!

On May 17 at 8:39pm, a magnitude 4.7 earthquake hit Los Angeles, centered over the airport. Two days later, a 4.0 earthquake hit the same location. Various small shocks occur constantly in the area, but these two were big enough to be felt, and eerily close to one another.

Living in California comes with a certain baseline of anxiety. I experienced the 1994 Northridge Quake, which was of magnitude 6.7 and killed 72 people, causing $20 billion in damage. (earthquake magnitudes are logarithmic – one extra point represents 30x more power.) From my house 13 miles away it felt like a gentle rocking and did very minor damage, but it was ruinous to other areas.

As a local, I stopped worrying long ago. There is no way to control quakes, and after not dying for a few years we tend to forget about the problem. There are many dangers to be afraid of but worrying constantly is foolish – but perhaps we are foolish not to take some consideration of the risks.

California straddles two continental plates, the Pacific and North American. The western half of the state is moving Northwest at a rate of two inches per year, and will theoretically be a part of Alaska in a million years. Fears of the “big one,” then, describe two quakes: a large one that is likely to occur soon, and a gigantic one far in the future that will finally separate the West from the mainland. A sobering thought: the USGS estimates that a magnitude 6.7 quake has a 99.7% chance of striking California in the next 30 years. When or where, however, is a mystery.

So should Californians be worried? In the short term, probably not. A very smart guy says that clusters of earthquakes occur all the time and help to relieve tension; more worrisome is a period of no earthquake activity. In the long term there will be disaster, but your chances of injury or major property loss our still small. There are dangers lurking in every city, and I still say that living in the beautiful state of California is more than worth the risk.

Want another helping of fear? Check out the five largest California earthquakes.



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