Composite volcanoes, also known as stratovolcanoes, are cone-shaped volcanoes located on convergent plate boundaries. Stratovolcanoes are formed when magma finds its way out of a fissure, and flows a long way. they are built in many layers by multiple eruptions. Many of the stratovolcanoes have a main vent that runs through the middle of the volcano, and ends at the peak, where it opens up into a crater. Stratovolcanoes are known to have violent eruptions that devastate the surrounding area for miles. in 1980, Mt. St. Helens the stratovolcano erupted and destroyed all wildlife around it. The explosion caused a landslide on the northern flank of the mountain, and took the lives of 57 people.