On July 8, 2006, at 12:39 pm ADT (8:39 pm UTC) a strong earthquake, magnitude 6.6, occurred in the Andreanof Islands region of the Aleutian Islands. The mainshock was preceded by a series of moderate foreshocks that began on July 1.

The mainshock was felt in Adak.

This earthquake is the largest to occur in this region since the magnitude 6.8 event on June 14, 2005. The July 2006 earthquake sequence occurred in the area separating the rupture zones of the 1965 M8.7 Rat Islands earthquake to the west and the 1957 M8.6 Andreanof Islands earthquake to the east.