Thursday, June 24, 2010

Hudson Valley Earthquake

Now this pisses me off.  I'm in Seattle, the heart of the Cascadia subduction zone where the potential exists for huge earthquakes, and every at home in the Hudson Valley of New York feels one on June 23.

Not that I want to experience a magnitude 6+ earthquake, especially in someplace like downtown Seattle where it will be incredibly devastating, but I've never really felt one with one exception.  Many years ago, when living in Albany, NY, I was laying in bed when I thought I felt a jolt.  Didn't think anything about it until later when I got onto the computer and saw there was a small earthquake in the northern Adirondacks.

The 5.0 magnitude earthquake on Wednesday 1:42 pm EDT was located 35 miles NNE of Ottawa, Canada and felt hundreds of miles away.  It occurred 12 miles down in the crust in an area called the Western Quebec Seismic Zone, an area of deep ancient faults that formed hundreds of millions of years ago and are periodically reactivated by stresses within the crust.

Northeastern earthquakes, unlike western earthquakes in places like California, are typically felt over much larger areas because the deep basement crust in the northeast is more intact and the seismic waves can propagate easier.  In the western U.S., the crust is heavily fractured and the waves attenuate and weaken with distance more quickly.

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