Cinder cones form from lava that breaks into small pieces after eruptions. The pieces harden into cinders and build up around a single vent, forming a cone that is circular or oval, according to the U.S. Geological Society. Cinder cones are typically small and are the simplest of volcanoes. They grow to heights of only about 1,000 feet and often have a rounded crater at the top. Paricutin Volcano in Mexico is a cinder cone.
Stratovolcanoes have symmetrical cones with steep sides that can rise to as high as 8,000 feet. Such volcanoes have either a crater with a single central vent or a cluster of vents that are part of a conduit for magma flow. Stratovolcanoes consist of layers of lava flows, ash, cinders and blocks. Lava flows from breaks in the crater or fissures on the sides of the cone. Fujiyama, Mount St. Helens and Mount Rainier are all stratovolcanoes.
Shield volcanoes have a broad sloping cone that forms from repeated lava flows that pour out from a central vent or group of vents and spread out over a wide expanse. The Hawaiian Islands include a chain of shield volcanoes. Mauna Loa is 13,655 feet above sea level -- it is the world's largest active volcano as well as the world's largest shield volcano. Oregon and northern California also feature shield volcanoes.
Most volcanic eruptions are relatively weak. About 60 volcanoes erupt every year, according to the U.S. Search and Rescue Task Force. An eruption is not necessarily explosive. Typically, thin and liquid magma will flow rather than explode out of a volcano. Although the flow may not be rapid, it still can destroy buildings and objects in its path. Thicker magma explodes because gases trapped inside it escape violently -- such eruptions can be deadly, and can bury and suffocate entire communities.