How dose volcanoes explode?
The stuff that comes out of volcanic explosions is either the molten rock called lava, or by-products of the lava and its intense heat. The Earth’s surface is made of floating plates of rock. Where these plates meet, they are either pushed up together (forming non-volcanic mountains) or one plate is pushed down. A plate being pushed down causes a plume of molten material to force its way up through the Earth’s crust, causing a volcanic hotspot. Volcanoes form over these hotspots. Eruptions are caused by a build-up of pressure under a volcano. The molten rock is still pushing its way upwards, but cannot make headway, causing pressure to increase for so long as there is still hot material trying to rise to the surface. Finally, the surface gives way and there is a volcanic eruption. As a general rule, the longer the interval between eruptions at an active volcano, the worse the explosion is going to be. Mount St. Helens, for example, was characterized by small eruptions in the early-to-m
