Susitna Glacier, Mountain glacier in central Alaska, United States

Susitna Glacier is a 36 km long valley glacier in the Alaska Range, fed on the south flank of Mount Hayes. It flows southwest, then west, then southwest again, gathering tributary glaciers from Mount Balchen in the west to Moby Dick in the east. Its lower end sits at about 850 m, is 3.4 km wide and forms the source of the Susitna River.

The glacier sits in a tectonically active region where a powerful 7.9 magnitude earthquake in 2002 revealed previously unknown geological faults beneath the ice. This event helped scientists better understand the hidden geological structures that lie under the glacier.

The glacier gives its name to the Susitna Glacier fault, which ruptured in the 2002 Denali earthquake. The fault had not been mapped before the quake, and its thrust movement was identified only after the event, making the glacier a reference point in Alaska Range seismology.

The best time to observe the glacier is during warmer months when access to the ice landscape is clearer and weather patterns are more stable. Visitors should prepare for alpine conditions since the location is remote and weather can change rapidly.

The 2002 Denali earthquake, magnitude 7.9, began with thrust movement on the Susitna Glacier fault, which had not been recognized before. The fault lies beneath the glacier, so the ice flows over a seismically active area.