On February 4, 1965, a magnitude 8.7 earthquake occurred on the Aleutian Megathrust in the Rat Islands region of Alaska. This earthquake is currently the eight largest earthquake ever recorded. The larger red star is the location of the earthquake. The smaller red star is the March 30, 1965, magnitude 7.5 earthquake. The white circles show the aftershocks of the earthquake. The line encircling the region shows the rupture area. This is defined by the distribution of the aftershocks.