According to the U.S. Geological Survey, geologists have identified four types of volcanoes. Cinder cones are the simplest type of volcano, followed by shield volcanoes, composite volcanoes and lava domes.
Cinder cones, such as Mexicos' Paricutin, consist simply of loose tephra, or volcanic debris. They tend to be fairly small, up to 1000 feet in height and a mile across, with steep sides and a small crater. Shield volcanoes, such as the Hawaiian Islands and Iceland, are formed almost entirely of cooled lava flows and can be tens of thousands of feet high and miles across at the base. Composite volcanoes are a blend of both lava flows and tephra, and are generally similar in size to shield volcanoes. Examples of composite volcanoes include Vesuvius, Vulcano and Mount St. Helens. Lava domes are rounder in shape and form when lava erupts very slowly.Learn More
The three major types of volcanoes are the cinder cone, the shield volcano and the stratovolcano. Each type differs in shape, size, erupted materials and eruption type.Full Answer >
The Earth has approximately 20 known supervolcanoes, according to James Morgan, who write for the BBC News. What constitutes a "supervolcano" is not clearly defined, so the term is avoided in the literature, but it is often used in reference to two distinct phenomena.Full Answer >
It is hard to put an exact figure on the number of extinct volcanoes in the world; according to Oregon State University, the expectation that a volcano will never erupt again is no guarantee that this is actually the case. When it comes to predicting volcanic behavior, there is a lot of potential room for human error.Full Answer >
Volcanic vents allow the Earth to release built up gases from the heat and pressure emanating from its core. Magma rises towards the surface, and as the pressure builds the magma seeks outlets through which to flow. The higher the pressure build-up, the greater the volcanic explosion.Full Answer >