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Google Earth Tour: The Faults of Flagstaff, Arizona

This 4-minute Google Earth flight examines the Lake Mary and Cataract Creek Fault systems near Flagstaff, Arizona. The 25-mile-long Lake Mary fault extends from Mormon Lake north to the city boundary of Flagstaff. It comprises dozens of active fault strands. If the entire fault ruptured, it would produce a M7 earthquake that would damage and crumble unreinforced masonry buildings in downtown Flagstaff.  

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Rupture along the length of the fault is unlikely. But according to Dr. Dave Brumbaugh (Northern Arizona University Professor Emeritus), rupture of just one or two fault strands could produce a M6 to M6.3 earthquake.

Forty-five miles north-northwest of Flagstaff, lies the Cataract Creek fault system. This broad fault system includes dozens of fault strands with an areal extent of 20 miles north-northwest and 10 miles wide. Three M6.0 events that struck Flagstaff in 1906 and 1912 are thought to have originated here. In 1993, a M5.3 earthquake on the Cataract Creek fault rocked Flagstaff and the nearby community of Valle.

Fault symbolization of Quaternary faults: Sources: Arizona Geological Survey & U.S. Geological Survey

  • Green line segments – young active faults.
  • Blue line segments – older active faults.
  • Black line segments – faults of indeterminate age.

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