On July 22, 2020, a major M7.8 earthquake struck the Shumagin Islands region of the Aleutians, just south of Simeonof Island.

The pie chart here shows the energy comparisons between the Simeonof mainshock, the two M6.1 aftershocks, the energy for all 16 aftershocks between M5 and M5.9, and the energy for all other aftershocks. Energy increases by a factor of 32 with each magnitude unit. Here you can see that the mainshock carries a significantly larger share of energy. Even though large magnitude aftershocks can sometimes feel just as intense, they do not actually release nearly the same amount of energy.