This map from the Utah Geology shows the Yellowstone supervolcano hotspot and its impact on earthquakes "downstream" as the North American plate moves across it. You can read the whole report in pdf format (it focuses on the Wasatch fault but applies to Borah). The two most powerful 20th Century earthquakes in the Lower 48 outside of California (where the North American plate grinds against the Pacific plate) were in this area.
: Function ereg() is deprecated in /home/america/public_html/content/gallery/lib/popup.php
on line 33