Taku Glacier on the Move Again: Active Deformation of Proglacial Sediments

Taku Glacier has begun to re-advance at a rate of 30 cm/day through the summer of 2001. The advance of the ice has led to striking deformation of the proglacial sediments. The compression by advancing ice has caused the outward propagation of at least two prominent bulges: the more distal (width 35 m, height 3 m) at a rate of about 10 cm/day; and the more proximal (width 80 m, height 4.5 m) at a rate of 15 cm/day. There are no visible thrust faults in the sediments, but shear must be occurring as part of bulge propagation. Over 55 km long and 700 sq km in area, Taku Glacier is the primary outlet glacier from the Juneau Icefield which mantles the Coast Mountains near Juneau, Alaska. The terminus of Taku Glacier advanced 7 km between 1890 and 1990, then remained nearly stationary over the next decade. However, the terminal region continued to thicken, with surface elevation rising at an average rate of 1.4 m/yr. Previous work showed that this glacier is actively excavating soft sediments and entrenching itself into these sediments as its terminus continues to grow and advance.