Aleutian Trench

The Aleutian Trench (or Aleutian Trough)^[1] is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for 3,400 kilometres (2,100 mi) from a triple junction in the west with the Ulakhan Fault and the northern end of the Kuril–Kamchatka Trench, to a junction with the northern end of the Queen Charlotte Fault system in the east. It is classified as a "marginal trench" in the east as it runs along the margin of the continent. The subduction along the trench gives rise to the Aleutian Arc, a volcanic island arc, where it runs through the open sea west of the Alaska Peninsula. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates. Here, the Pacific plate is being subducted under the North American plate at a dip angle of nearly 45°. The rate of closure is 7.5 centimetres (3 in) per year.^[2]

The Pacific plate subducting under the North American plate, leads to increased faulting. This subduction began in the Early Cretaceous and continues into the present day. Within and near the Aleutian Island arc and depending on the location, there is thrust faulting, strike-slip faulting, and normal faulting. These result in an increased amount of seismic activity. Earthquakes can reach magnitudes between 7–8.5.^[3]