Volcano

• volcano is a rupture in the crust of a planetary-mass object
• Volcanoes can also form where there is stretching and thinning of the crust's plates
• The word volcano is derived from the name of Vulcano,
• The study of volcanoes is called volcanology
• When rocks become so hot, they can become a substance called magma
• . Lava flows are the molten rock that oozes onto the Earth’s surface after a volcano eruption.
• Magma that erupts is called lava
• Volcanic Bombs - These molten rocks are thrown out from a volcano and are at least 66mm in size.
• Lava dome - These circular mounds protrude from volcanoes because of the slow release of viscous lava.
• Lava Dome - When lava is too thick and sticky, it piles up around the vent and forms a dome
• Eruption Column - These clouds of heated ash and tephra are released from a vent during an explosive volcanic eruption.
• Eruption Cloud - Ash falls back down like powdery snow
• magma blasts up into the air and breaks apart into pieces called tephra.
• Acid Rain - When sulfur dioxide and nitrogen oxide emitted from volcanoes reacts with water molecules in the air
• Tephra can range in size from tiny particles of ash to house-size boulders.
• Pyroclastic Flow - This type of deadly flow contains fastmoving volcanic matter and hot gas
• Lahar - When hot volcanic material mixes with water from streams or snow and ice
• Fumaroles create pathways for rising heat, volcanic gas, and magma
• Fumaroles Holes, cracks, or fissures - They emit steam and volcanic gases, such as sulfur dioxide and carbon dioxide.
• Cracks and fumaroles act like a window so scientists can get a glimpse of the gases inside volcanoes.
• active volcano is one which has recently erupted and there is a possibility that it may erupt soon.
• dormant volcano is one that has not erupted in a long time but there is a possibility it can erupt in the future.
• extinct volcano is one which has erupted thousands of years ago and there’s no possibility of an eruption.
• Cinder Cones  - These are circular or oval cones made up of small fragments of lava from a single vent that have been blown up
• Composite volcanoes are steep-sided volcanoes composed of many layers of volcanic rocks, usually made from high-viscosity lava, ash and rock debris.
• Shield volcanoes are volcanoes shaped like a bowl or shield in the middle with long gentle slopes made by basaltic lava flows
• Lava Domes - are formed when erupting lava is too thick to flow and makes a steep-sided mound as the lava piles up near the volcanic vent.
• The intensity of explosive volcanism is expressed using the Volcanic Explosivity Index (VEI)
• Magmatic eruptions are driven primarily by gas release due to decompression
• Hawaiian eruptions are typical of volcanoes that erupt mafic lava with a relatively low gas content
• Strombolian eruptions are characterized by moderate viscosities and dissolved gas levels
• Strombolian eruption - They are characterized by frequent but short-lived eruptions that can produce eruptive columns hundreds of meters high
• Vulcanian eruptions are characterized by yet higher viscosities and partial crystallization of magma, which is often intermediate in composition.
• Peléan eruptions are more violent still, being characterized by dome growth and collapse that produces various kinds of pyroclastic flows
• Plinian eruptions are the most violent of all volcanic eruptions.
• Plinian eruption - They are characterized by sustained huge eruption columns whose collapse produces catastrophic pyroclastic flows.
• Phreatomagmatic eruptions are characterized by interaction of rising magma with groundwater
• Phreatic eruptions are characterized by superheating of groundwater that comes in contact with hot rock or magma
• Lava flows are rivers of incandescent of molten rock or lava moving downslope or away from an eruption vent.
• Tephra or ash propelled through the atmosphere in an eruption plume or an eruption column eventually fall or gravitationally settle over areas downwind of an erupting volcano,