POTSDAM An earthquake in southern Quebec was felt far into St. Lawrence County.
The temblor, measuring 4.2 on the Richter scale, occurred 31 miles east of Ottawa, Ontario, along the Ottawa River just after 4 a.m. Tuesday. Its effects were felt as far away as Potsdam and Massena.
People felt it, but it is too small an earthquake to cause damage, said Frank R. Revetta, SUNY Potsdam geology professor. They usually dont cause damage until theyre up into the fives.
For decades, Mr. Revetta has tracked earthquakes along a belt from the Adirondacks into western Quebec.
No one knows for sure why they happen, he said. The favored theory is that they are due to the reactivation of old faults due to stresses in the earth.
Though researchers have found a pattern of tremors, the fault line causing the quakes remains elusive, Mr. Revetta said.
They are beneath the surface, he said. Earthquakes help locate them, but in New York most earthquakes occur along faults that dont reach the surface, making it difficult to map out the fault.
Mr. Revetta said most of the areas quakes arent powerful enough to cause damage, but still can be felt.
These earthquakes are quite common, but most of them are shallow; that is why they are felt by so many people, he said.