Stratovolcanoes erupt explosively as they are usually found at a destructive plate margin. They have also been responsible for the largest, most destructive historic eruptions due to retention and build-up of volatile gases within the volcanos and their magmas during their pre-eruptive phases. During any given year, a few dozen stratovolcanos are active, and around 500 have erupted during historic times.
Stratovolcanoes are also called "composite volcanoes" because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes. A famous stratovolcano is Krakatoa, best known for the eruption in 1883.
Cross Section of Stratovolcano
Composite Volcano on an Aleutian Island