Why isn’t there a single volcano at the convergence of Indian and Eurasian tectonic plate?
In: Earth Science
To get volcanoes, you need magma in the upper mantle to become liquid (although very hot, the mantle is actually still solid-ish due to pressure). To get this liquid magma, you can either reduce the pressure until it melts (which happens at divergent plate margins) or you can alter the chemistry of the rock. When oceanic crust subducts, it pulls water down with it. This water hydrates the magma, which allows it to melt at temperatures and pressures it normally wouldn’t. From there, the magma rises into the crust.
At the point India and Eurasia meet, there is no water-saturated sediment subducting, so the rock of the mantle doesn’t melt.
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