Final answer:
Factors affecting the isotherms in subduction zones include the angle of subduction, the presence of water that lowers the mantle's melting temperature, and convection currents, which lead to variations in heat transfer and volcanic activities closer to coastal lines.
Step-by-step explanation:
The student is asking about factors that affect the isotherms (lines of equal temperature) in subduction zones, as well as consequences related to these phenomena. In a subduction zone, several factors can affect the temperatures and thus the isotherm positioning, including:
- The angle of subduction, which can affect the depth at which the plate reaches high temperatures and the related seismic and volcanic activity.
- The presence of water, which can lower the melting temperature of the mantle above the subducting plate, leading to magma production.
- Convection currents within the Earth, which can redistribute heat and affect the thermal gradient in a subduction zone.
Regarding volcanism, volcanoes tend to be closer to the coastline in subduction zones where the subducted slab melts at a shallower depth due to factors such as the angle of subduction or the amount of water released from the subducting plate.