earthquakes

The border near Arkansas and Missouri was the site of an extraordinary series of earthquakes in 1811 and 1812 that included four earthquakes estimated to be magnitude 7.0 or larger. These earthquakes changed the course of the Mississippi River and even caused the river to flow backwards for several hours.

Hawaii has had its many earthquakes, two in 1868, one in 1871 and one more in 1975. MOst of these occured on or near 'Big Island' where there are active volcanoes.

In Alaska the rocks of the Pacific Ocean are being subducted underneath the continental rocks of Alaska. This activity has created at least twelve magnitude 7.0 or larger earthquakes in just the last 30 years.