Final answer:
Asthenospheric upwelling beneath continental lithosphere can result in the formation of volcanoes, with volcanic arcs often located near coastlines depending on subduction dynamics.
Step-by-step explanation:
Asthenospheric upwelling beneath continental lithosphere can cause various geological phenomena, one of which is the formation of volcanic activity. As the hot and plastic asthenosphere rises, it may undergo partial melting due to decreased pressure or the addition of volatiles like water from a subducting plate.
This partial melting can lead to the creation of magma, which can rise through the lithosphere and result in the emergence of volcanoes. The proximity of these volcanoes to coastlines depends on the specifics of plate tectonics in the region.
For example, where an oceanic plate subducts beneath a continental plate, as off the west coast of South America, this process can create a volcanic arc that is relatively near the coastline due to the angle of subduction. Additionally, the added weight on the lithosphere from tectonic events can cause bending and the creation of foreland basins, as was the case with the formation of the Persian Gulf during the collision of the Asian and Arabian plates.