Re: 5.0-magnitude tremor more info

From http://news.nationalpost.com/2010/06/23/tremors-felt-in-toronto-ottawa-reports/

The earthquake that was felt across Eastern Canada and the Eastern United States was likely caused by a geological phenomenon called “isostatic rebound,” said University of Toronto geologist Russell Pysklywec.

Most of North America was buried two kilometres of ice 10,000 years ago, he explained. Since then the earth has been slowly rebounding back to its pre-ice age levels.

He said it was like a steel plate on a piece of Styrofoam and as the plate is lifted the foam begins to reform — but not right away.

The Ottawa Valley is particularly vulnerable because of a major fault that runs through the area.

“The Ottawa River is essentially a huge fault. When tremors begin deep in the earth, about 20 km down, it looks for a place to focus that energy, and a fault is the best place for that to happen.”

He said the tremors will have been recorded all around the world because the amount of energy is so huge that it can travel half way around the globe in 20 seconds.

Some of the major cities that felt the June 23rd earthquake