Wednesday, August 24, 2011

Shakedown Street

We had an earthquake in Washington, DC, yesterday. Not just a slight trembling of the ground, mind you. This one was a magnitude 5.8 (or 5.9), which is a good-size temblor, even for places that get earthquakes regularly. For us, it didn't feel like anything unusual, but then, my office is on the first floor and our building has only one floor. At first, I thought the airconditioner in our building, which is on the roof and had been having issues for the past month or so, had kicked on with a vengeance. But then our emergency crew evacuated the entire building to the parking lot (later, we learned that's not what you're supposed to do in an earthquake). I've been through quakes before, when I was at Stanford, and I didn't think this was much of a shake - until news reports came in and said it was 5.8 and centered around Mineral, Virginia, which is not far from Fredricksburg. The news also mentioned that this one was felt as far north as MIT.

DC reacted the way it usually does to things like this - or snow events. Everyone went into a controlled panic, which is kind of like the controlled skid an SUV does on black ice - right into the guardrail. An hour later, all the Federal employees were sent home, and that's when the chaos began. Metro was first shut down and then reopened at slower than normal speeds - trains were running at 15 miles an hour. Freeways and downtown streets clogged up suddenly and so firmly that people didn't get home for hours. The next morning, several school districts decided to close; it seems they hadn't determined that the buildings were structurally safe. The Feds went on liberal leave. Three of the parapets on the National Cathedral had cracked and fallen off (it took them 90 years to finish the building, and look what happens!), and even the newly restored (in 2000) Washington Monument had developed cracks in some of the marble blocks.

Sure it sounds bad, but the Loma Prieta earthquake in San Francisco was worse. Occurring in 1989 at the very moment the World Series game between the San Francisco Giants and the Oakland Athletics was in progress, the temblor heralded the birth of my nephew and Barely Brothers bassist, Earthquake Sam, in a Bay Area hospital. It measured 6.9 on the Richter scale, which is a pretty good jolt. Buildings collapsed, water lines and gas lines ruptured, a section of the elevated freeway in Oakland collapsed onto the level below it, huge fires started in various rowhouses and a section of the Bay Bridge collapsed, snarling the commute from Oakland to San Francisco for months thereafter. Portions of the Stanford campus were damaged as well, but my aunt's bungalow stayed upright. There were only 63 deaths reported, which is incredibly fortunate.

I missed it all, being in Texas. But when I was at Stanford, there were no fewer than three earthquakes. These were not terribly big shocks; I don't think there was anything greater than a 5.3 magnitude. But I did get to spend an ominous couple of minutes one afternoon on the 12th floor of a San Mateo office building watching the light poles in the parking lot outside swaying back and forth like a metronome set on 212. And my supervisor's bookshelf collapsed onto what would have been his head had he not been in St. Louis on business.
Texas does not get earthquakes. Or rather it didn't - until the Barnett Shale got drilled. About ten years ago, a very lucrative deposit of natural gas was discovered under the Dallas-Fort Worth International Airport, and every exploration company wanted a piece of it. The problem was getting the gas, given its location. The gas companies had always been capable of directional drilling (which in the '50s was called "slant hole" drilling and was a clever bit of piracy that allowed an enterprising wildcatter to filch his neighbor's oil or gas deposits) to get at the gas without disturbing the airport, but the gas was trapped in rock layers that wouldn't yield very easily - unless high pressure fluids were pumped in to break the rocks and push the gas out. This process - hydraulic fracturing, or "fracking" - is sort of like a power enema and has proved very good at dislodging the gas deposits. But recently, residents of Tarrant County noticed that a whole lot of "fracking" earthquakes were occurring, as the ground settled into the pockets where the gas had been. These were not big shakers - averaging no more than 3.0 on the Richter Scale, but they were noticeable, and they occurred with unnerving frequency. The same thing has also happened in places in Arkansas where gas deposits have been tapped, and appears likely to happen in Pennsylvania when those gas fields get drilled.

That's Fort Worth. Houston is very seismically inactive - probably because it sits on a thick layer of sedimentary clay, or gumbo. It doesn't shift so much as it oozes, and it has a tendency to shrink and swell with the amount of groundwater that accumulates during the rainy season. When it oozes (which it does constantly), it plays havoc with foundations and pavements - so much so that homes have been known to slowly grow wall cracks and cracked foundations (and for some reason known only to the shoddy workmanship of the local homebuilders, those show up rather quickly on homes built within the past ten to twenty years).

Meanwhile, back on the East Coast, earthquakes, while infrequent, have been known to occur and to be intense enough that there are seismic requirements in the building codes for communities in the Washington region. This seems prudent, given the worst earthquake to occur east of the Mississippi hit Charleston, South Carolina, in 1886 and registered 7.3 on the Richter scale. The Mississippi River itself was the scene of the strongest earthquakes in the Lower 48, which hit New Madrid, Missouri. There were at least four them over a one-year period beginning in 1811, with the strongest being perhaps an 8.0, or greater than the San Francisco earthquake of 1906. And the grand-daddy of them all was the Good Friday Earthquake that hit Alaska in 1964 and measured 9.2. While we were not hit as hard as either San Francisco or Charleston or Alaska or Missouri this time, the odds are that we were be due for one. And when the next big one hits, people will again react like there's 10 inches of snow on the ground.

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