The geological feature responsible for the volcanic activity in this part of the world is the convergent tectonic boundary between the North American tectonic plate and the Pacific tectonic plate.
The Aleutian Islands are part of the so called ''Ring of Fire''. This means that they are part of the most active volcanic chain in the world. This is due to the convergent boundaries between the Pacific tectonic plate from one side, and the North American, South American, Eurasian, and Australian tectonic plate from the other side. The Pacific plate is submerging bellow all of them, and this contributes to the release of lots of magma and pressure towards the surface of the Earth, thus creating volcanoes in close proximity to the tectonic boundaries.
