yes there is a fault line that basically runs south from canada and both Boston and Manhattan lie on top of it. It is this fault line that casued that massive quake in Maine years ago, and a very large earthquake in New York city sometime during the 19th century.
Another reason for quakes in the northeast regeion is that during the ice age enormous glaciers covered most of the area and they averaged up to a mile thick. Under the weight. the earths crust was compacted so much that to this day there are still small tremors ocuring regularly as the crust decompresses. These tremors are not very strong and are usually less than that of what is created when a heavy truck drives by, so most go un noticed but are recorded my the geological survey, but are not reported to the public becasue of their miniscule proportions.
