The Magma Reservoirs

The rocky innards of the Earth locally melt to produce magma, which sometimes erupts as cataclysmic explosions. The energy released by these eruptions is matched only by that of large meteorite impacts. Whether large pools of magma generate huge volcanic eruptions, whose volume and duration can have global consequences for humanity, or solidify slowly within the Earth’s crust to form plutons (bodies of magmatic rock that crystallize at depth beneath volcanic areas) depends primarily on what happens in magma reservoirs in the upper 10–15 km of our planet. These reservoirs are built over time spans of 105–106 years and cannot be observed directly. What goes on inside them, and what dictates their fate? We are only beginning to unravel their inner workings.