Volcanoes are one of Earth’s most terrifying—and exhilarating—spectacles. These vents in the ground issue lava, ash, and noxious gases at temperatures as high as 2,100°F (1,150°C) and are the closest we’ve ever gotten to the churning engine that keeps our planet running. What causes them to erupt?
Magma, or molten rock, collects in chambers beneath Earth’s surface. As magma accumulates, pressure in the magma chamber increases. If the pressure gets high enough, overlying rocks break, allowing the magma to escape as lava.