VOLCANO ERUPTION HOW DOES A VOLCANO ERUPTS? DIFFERENT TYPES OF VOLCANIC ERUPTION Prepared by:Group 3 HOW DOES A VOLCANO ERUPTS? • There are primary factors affecting the volcanoes eruptive style:the magma’s temperature,it’s chemical composition,and the amount dissolved gases it contains. • Viscosity is the property of the material’s resistance to flow. • The more vicous and thicker the material is,the greater is its resistance to flow. DIFFERENT TYPES OF VOLCANIC ERUPTION VOLCANOES ERUPT DIFFERENTLY.THEY ARE GENERALLY CLASSIFIED AS WET OR DRY DEPENDING ON THE MAGMA’S WATER CONTENT. VOLCANOES ARE DESCRIBED ACCORDING TO THE STYLE OF ERUPTION AS FOLLOWS: PHREATIC OR HYDROTHERMAL ERUPTION PHREATIC OR HYDROTHERMAL • is a stream-driven eruption as the hot rocks come in contact with water. • It is shortlived, characterized by ash columns but may be an onset of a larger eruption. • A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption • The extreme temperature of the magma (anywhere from 500 to 1,170 °C (932 to 2,138 °F)) causes near-instantaneous evaporation to steam, resulting in an explosion of steam, water, ash, rock, and volcanic bombs. PHREATOMAGMATIC ERUPTION PHREATOMAGMATIC • Is a violent eruption due to the contact between water and magma. • As a result a large column of very fine ash and high-speed and sideway emission of pyroclastics called base surges are observed. • They differ from exclusively magmatic eruptions and phreatic eruptions. • Unlike phreatic eruptions, the products of phreatomagmatic eruptions contain juvenile (magmatic) clasts. STROMBOLIAN ERUPTION STROMBOLIAN • A periodic weak to violent eruption characterized by fountain lava. • relatively mild blasts with a volcanic explosivity index of about 1 to 3. • consist of ejection of incandescent cinder, lapili, lava and bombs, to altitudes of tens to a few hundreds of metres. • They are named for the Italian volcano Stromboli. VULCANIAN ERUPTION VULCANIAN • characterized by tall eruption columns that reach up to 20 km high with pyroclastic flow and ashfall tephra. • Mercalli described vulcanian eruptions as "...Explosions like cannon fire at irregular intervals..." • The term vulcanian was first used by Guiseppe Mercalli, witnessing the 1888– 1890 eruptions on the island of Vulcano. • Their explosive nature is due to increased silica content of the magma. PLINIAN OR VESUVIAN ERUPTIONS PLINIAN ERUPTION OR VESUVIAN ERUPTIONS • excessively explosive type of eruption of gas and pyroclastics, just like our Pinatubo Volcano in Zambales. • Plinian/Vesuvian eruptions are marked by columns of volcanic debris and hot gases ejected high into the stratosphere, the second layer of Earth's atmosphere. • The key characteristics are ejection of large amount of pumice and very powerful continuous gas-driven eruptions. Trivia Photographer Thomas vdW accidentally captured the bright streak of a falling meteor as he shooting an erupting volcano during a photography trip to Kamchatka,Russia.
