Friday, August 2, 2002
Carlisle Comments Earthquakes threaten Carlisle and New England
Around 6:50 a.m. on Saturday, April 20, an earthquake struck fifteen miles southwest of Plattsburg, New York. Many in Carlisle experienced the earthquake that was "felt" from Toronto to Baltimore. Locally, the quake was only strong enough to rattle a few dishes. Like most other teenagers, on a Saturday morning, I was sleeping late and felt nothing at all.
This is not the last quake that will hit this region, nor will it be the weakest. Just last year there were twenty-two earthquakes in the state of New York alone, though all were minor. Are these small earthquakes a prelude to something bigger and more destructive?
One theory regarding the occurrence of earthquakes in the northeast revolves around the fact that glaciers once covered this region nearly 11,000 years ago. As the glacier melted, weight was gradually removed from the ground. The land that had been depressed under thousands of feet of ice began to rebound, a process known as isostasy. It is possible that the abundance of small earthquakes is a result of the earth rebounding.
Another theory suggests that the earthquakes are a result of plate tectonics. Scientists believe that around twenty plates of crustal rock float over a semi-liquid mantle, and that is how they explain most geological phenomena. Usually, earthquakes occur as these plates of rock bump into, slide past, or move away from each other. It is believed that in addition to these normal plate movements, the Northeast is being affected by the mid-ocean ridge. The mid-ocean ridge is a diverging (spreading apart) plate boundary that encircles the world, like the stitches of a giant baseball. Areas around it have the most seismic activity; it has great influence over the seismic activity of the entire world. The mid-ocean ridge pushes on the plate of North America at the rate of one inch per year. To the west, the North American plate is stopped from moving by the eastward moving Pacific plate. As the mid-0cean ridge spreads apart, it puts pressure on the North American plate. New England actually lies close to the center of the North American plate and as the pressure builds, the plate buckles. The buckling could cause a massive earthquake in our area. It has been calculated, from studying past earthquakes, that an earthquake of this nature should happen about every two hundred years or so. The last major earthquake to hit our area happened in 1755 around Cape Ann, Massachusetts. The earthquake was even felt in Carlisle and Concord, toppling chimneys, breaking windows, and cracking foundations.
New England is overdue for a major earthquake by about fifty years. The not-so-obvious quakes felt over the years have most likely just been precursors to the "big one." How does this affect the citizens of Carlisle, and what can be done about it? FEMA, the Federal Emergency Management Agency, gives a lot of suggestions for what to do before and after an earthquake, some obvious and some not so obvious.
Because all of these suggestions can be found at their web site (http://www.fema.gov/library/quakef.htm), I will mention the most interesting and the most important precautions to take. First of all, before an earthquake even happens, it is important to secure things in one's home that might be a danger to someone if they fell, including shelves and the things on them, glass food containers, and picture frames. Shelves should be secured and the heavier things on them should be placed near the bottom. Glass food containers should be put in closed cupboards near the floor, and picture frames should be hung somewhere other than where one might be caught unawares as they fall; they shouldn't be hung over beds and couches. Also, water heaters should be secured, and you should have a system for turning off gas, electricity and water lines. During an earthquake, you should brace yourself against an inside wall or under furniture, so any falling debris could not injure you. You should also make sure to stay away from windows or any unsecured bookcases or other items that might topple over. If outside or in a car, it is important to be in an open place away from building or trees or power lines. If you are inside when the earthquake starts, do not attempt to exit; it is better to stay alert to any objects falling around you. After an earthquake, it is important to be careful around pets, whose behavior may be erratic. Also, you should call water, electric, and gas companies if you suspect something is wrong. There are countless things that should be done before, during, and after an earthquake. Since I could not list them all here, I suggest going to the very informative FEMA web site, listed above.
The most important thing to remember when dealing with earthquakes is that they are a surprise, even when they are suspected to be on the way; no one really knows when they are coming or how strongly they will strike. It is important to be prepared before, during and even after, to minimize damage and injury.
© 2002 The Carlisle Mosquito