Week 5 Converging Plates: The Aleutian Trench

Image credit: NASA

For this week’s travel post, I chose to write about a convergent-plate margin located at the North end of the Pacific ocean, between Alaska and Russia. This margin is known as the Aleutian Trench, and is home to a multitude of significant crustal deformations. The tectonic activity occurring at this convergence zone is subduction, with the oceanic Pacific Plate sliding underneath the continental North American Plate. A significant oceanic trench has formed along this subduction zone, and is over 2,000 miles long and 26,000 feet deep. 

The Aleutian Trench is home to a series of major thrust faults, which are collectively identified as the Alaska-Aleutian Megathrust fault. The compression forces along these faults have been responsible for some of North America’s most significant earthquakes. In fact, the Alaska-Aleutian Megathrust fault has been responsible for 9 out of 10 of the largest earthquakes ever measured in the U.S., with the 1964 Alaska earthquake being the largest.

Convergence of the North American and Pacific tectonic plates is responsible for more than just trenches and faults in this area. During the subduction process at this convergence zone, the Pacific Plate descends into the mantle, melts, and subsequently rises parallel to the Aleutian Trench. Over time, this accumulation of magma near the surface has led to the formation of a long chain of small islands called the Aleutian islands. This island chain consists of 14 large active volcanoes and 55 smaller ones, and is part of the famous “ring of fire” chain of active volcanoes in the Pacific ocean.

It is amazing to see such significant evidence of tectonic plate activity in one area! Between the deep trench along the subduction zone, the chain of active volcanoes on the continental side, and the intense seismic activity, there is no question that this geographic location is a convergent-plate boundary.