When supervolcanoes explode, they do so at a magnitude of 8, the highest and most destructive of the explosivity index. | National Geographic TV

In explosive eruptions, expanding gases tear #magma apart and shatter solid rock. Towering clouds of rocks, #ash and gas are thrust above volcanoes, reaching heights of several miles. Ash clouds are blown by the wind tens to hundreds of miles from the volcano. As the volcanic cloud drifts downwind, the material within them gradually falls to the ground. The thickest deposits form closest to the volcano, where buildings and land can be buried. Fine ash is transported farther from the volcano and