Just southeast of Grand Canyon, near Flagstaff, is Sunset Crater Volcano National Monument, where in A.D. 1064 a series of eruptions built the park’s namesake cinder cone. About 45 earthquakes occurred in or near the Grand Canyon during the 1900’s. Of these, five registered between 5.0 and 6.0 on the Richter Scale. Dozens of faults cross the canyon, with at least several active in the last 100 years.