The largest recorded
earthquake
in the United States was a magnitude 9.2 that struck Prince William Sound, Alaska on Good Friday, March 28, 1964 UTC.
On May 22, 1960 a great Mw 9.5 earthquake, the largest earthquake ever instrumentally recorded, occurred off the coast of southern Chile
an earthquake of magnitude 10 has not been recorded
Alaska and California have the most earthquakes (not human-induced).
thrust faulting on the subduction zone plate boundary between the Pacific and North America plates
a 9.9 magnitude earthquake has not been recorded
earthquake typically can be felt at many places as far as 60 miles from where it occurred