Final answer:
The recent volcanic activity in the Cascade Mountains is a response to the subduction of the Juan de Fuca Plate.
Step-by-step explanation:
The recent volcanic activity in the Cascade Mountains is a response to the subduction of the Juan de Fuca Plate.
Subduction is a process where one tectonic plate moves underneath another plate. In this case, the Juan de Fuca Plate is subducting or moving underneath the North American Plate.
This subduction creates a melting of the Juan de Fuca Plate, which then leads to volcanic activity and the formation of volcanoes in the Cascade Mountains.