Good question! I’m no geologist, but I guess in a long rift zone you could have different parts showing activity due to the same underlying cause.
It was very shallow and it would “ring” through the bedrock up the east coast. East of the Appalachian’s there is shallow bedrock with lots of “sand” from the glaciers on top of it. In a BIG one, the sand would liquify and cause lots of issues. That’s why it would be felt for a long distance.
Rift zone?
This was mid plate!