Last week's cluster of small earthquakes near Colorado City just south of the Utah border, generated interest in this remote area. Lisa Linville, who recently joined AZGS as an earthquake seismologist, based in Flagstaff, has written a nice overview on our Groundswell blog, which focuses on earthquake topics.
I'm reproducing Lisa's map here. The 4 earthquakes from Dec. 12-13, ranged in magnitude from 1.7 to 3.1 (shown in orange; other historical quakes in open circles). This cluster falls in between the Sevier-Toroweap and Hurricane fault systems, both of which are active.
We're not ready to link the quakes to a specific fault. Similar clusters of quakes are not uncommon throughout the region, many not associated with any known faults.
These earthquakes are a reminder that there is a significant seismic hazard potential in northwestern Arizona.