A volcano erupts through the build-up and release of pressure, whether that pressure is of its underlying magma, water or both. This release can be explosive, as it was in the famous eruption of Mt. Vesuvius that destroyed Pompeii, or it can be slow and effusive, as it is in the ongoing formation of the Hawaiian islands.
An eruption that is caused solely by pressures underneath the Earth is a magmatic eruption. In a phreatic eruption, underground water heated by magma forms compressed steam, fracturing and weakening the surrounding rock and ultimately resulting in an violent explosive eruption. A phreatomagmatic eruption is caused by the interaction of magma and water; as the water cools the magma, the resulting stress fractures destabilize the volcano, leading to an eruption.
Explosive eruptions are marked by the violent release of compressed gas, including steam and sulfuric compounds. An effusive eruption, on the other hand, contains little compressed gas and is marked by the gradual flow of lava to the surface. These are two extremes of a sliding scale, with rare Plinian and Ultra Plinian eruptions as the most explosive and continuous Hawaiian eruptions as the least. In general, the more frequent a volcanic eruption is, the less violent and explosive it is.Learn More
Various factors trigger a volcanic eruption. The three predominant factors are the magma's buoyancy, the pressure from the gases that separate in the magma and the merger of a new batch of magma with a chamber already filled with magma.Full Answer >
Examples of cinder cone volcanoes are Kula and Karapinar in Turkey; Taal Volcano in the Philippines; Hverfjall in Iceland; El Jorullo, Parícutin and Pinacate Peaks in Mexico; Mounts Leura, Fox and Elephant in Australia; Royal Society Volcano in Antarctica; Manda-Inakir on the Ethiopia-Djibouti border and Barren Island in the Andaman Islands. The United States hosts over 100 cinder cones, mainly in western states and Hawaii.Full Answer >
Make a volcano project by building a paper-mache volcano, measuring out the baking soda and adding vinegar. For this project, gather a 1-liter empty plastic bottle, a piece of cardboard, newspaper, flour, water, paint, dishwasher detergent, food coloring, baking soda and vinegar.Full Answer >
The most common and serious types of volcanic hazards are flowing lava, falling ash, glowing avalanches and moving mud and debris. The exact hazard level varies depending on the type of volcano erupting. Additional hazards include the emission of hazardous gases and eruption clouds, which are dangerous to planes and helicopters.Full Answer >