Final answer:
The Low Velocity Zone (LVZ) in the upper mantle is caused by partially melting mantle rock. Heating of the lithospheric region above a subducting plate and the presence of hot spots can lower the melting temperature of the rock, leading to magma production and volcano formation.
Step-by-step explanation:
The Low Velocity Zone (LVZ) in the upper mantle is probably caused by partially melting mantle rock. When the lithospheric region above a subducting plate is heated, the melting temperature of the mantle rock is lowered, leading to the production of magma.
Another way the rock can melt is through the presence of a hot spot, which is a region of increased temperature caused by mantle plumes. The hot spot can cause the lithospheric region to melt and result in the formation of volcanoes.