1. The New Madrid Seismic Zone (United States): Located in the central Mississippi Valley, this zone is far from any active plate boundary. The earthquakes here are thought to be caused by ancient, deep-seated faults that reactivated long after the tectonic plates shifted. The most famous New Madrid earthquakes occurred in 1811-1812, which were incredibly powerful and caused widespread damage.
2. The Charlevoix Seismic Zone (Quebec, Canada): This zone is situated in the middle of the North American Plate. It is believed to be caused by the reactivation of ancient faults that were created during the breakup of the supercontinent Rodinia, billions of years ago. These earthquakes are much smaller than those in the New Madrid Zone, but they still pose a risk to the region.
