Dave Brumbaugh is director of the Arizona Earthquake Information Center at Northern Arizona University, where he's also a geophysics professor.
Brumbaugh says the November quake is puzzling because it occurred on a fault line running in a northeasterly direction, while most other quakes in the area have been triggered by faults that trend almost northwesterly.
He says it's also interesting that the earthquake's foreshock and half of its approximately 20 aftershocks occurred on fault planes perpendicular to the main quake.
The Arizona Daily Sun that the November quake was the strongest felt in Flagstaff since a 5.3 magnitude quake in 1993.
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