23 August 2011

The Big East Coast Shake

Posted by Dan Satterfield

The view from two seismographs near the epicenter. The quake has been rated at 5.9 and was very shallow at 6 km. It was felt in Montgomery, Alabama and in Fredericton, New Brunswick. Will add more data on this page soon.

Oak Ridge Mass. Seismo. The VA quake is at bottom right. The quake at top may have been the Colorado Quake this morning (checking it is). Click for larger version

There are two types of earthquake waves. Body waves and surface waves. Body waves travel in the Earth and are either P waves or S waves. P waves are push-pull waves and S waves are vertical waves. On the surface another type of wave called a Rayleigh wave is similar to the action of an S wave, and it causes most of the damage. Michigan Tech Univ. has a great page showing these waves here.

Below is an animation of a Rayleigh wave from Mich. Tech. Notice how objects move in a circle as the wave passes. If you felt the quake today on the East Coast, you moved in a circle as well. The bigger the circle, the more you felt it!

From Mich. Tech Univ. Click for larger version- more on their web page linked in the post.

Callan Bentlley at Mountain Beltway has a lot more about the quake today and being a Geologist it is right up his alley!