When scientists examine the gases ejected during a volcanic eruption, the majority of the gas is water vapor. How does the process of subduction provide a water source for volcanic gases?

Why is earth's outer core hotter than earth’s oceanic crust? earth’s oceanic crust is denser than earth’s outer core is. earth’s oceanic crust has lava flowing from the mantle. earth’s outer core has a composition of solid iron and nickel. earth’s outer core is deeper within earth than oceanic crust is.