THE LAKE MARY FAULT AND FLAGSTAFF, ARIZONA

The Lake Mary fault system is a seismically active group of interconnected faults which at the northern end crosses through the heart of the city of Flagstaff, Arizona,an urban area of more than 70,000 people. The earthquake activity from the fault system has included earthquake swarms and tremors as large as magnitude MS 6.2 (1912). Fault plane solution analysis indicates that MW≥ 3.0 events are a response to NE-SW extension in a pre-fractured crust. The earthquake history, fault data, and estimates of potential ground shaking indicate that the Lake Mary fault system has the potential to produce earthquakes as large as MW 7.0 which could result in significant damage to Flagstaff.