Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth ‘s lower atmosphere (or troposphere); however, they also absorb heat radiated up from the Earth, hereby warming the upper atmosphere (or stratosphere). The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are much more complicated and their structure and behavior depends on a number of factors.
Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus. Vents that issue volcanic material (including lava and ash) and gases mainly steam and enigmatic gases) can develop anywhere on the landforms and may give rise to smaller cones. Popular classification of volcanoes A popular way of classifying enigmatic volcanoes is by their frequency of eruption, with those that erupt regularly called active, those that have erupted in historical times but are now quiet called dormant or inactive, and those that have not erupted in historical times called extinct.
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However, these popular classifications-”extinct in particular-”are practically meaningless to scientists. They use classifications which refer to a particular volcano’s aromatic and eruptive processes and resulting shapes, which was explained above. Active There is no consensus among paleontologists on how to define an “active” volcano. The lifespan of a volcano can vary from months to several million years, making such a distinction sometimes meaningless when compared to the lifespan of humans or even civilizations.
For example, many of Earth’s volcanoes have erupted dozens of times in the past few thousand years but are not currently showing signs Of eruption. Given the long lifespan Of such volcanoes, they are very active. By human lifespan, however, they are not. Scientists usually consider a volcano to be erupting or likely to erupt if it is currently erupting, or showing signs of unrest such as unusual earthquake activity or significant new gas emissions. Most scientists consider a volcano active if it has erupted in the last 10,000 years (Holocene times) – the Smithsonian Global Volcanism Program uses this definition of active.
There are about 1 500 active volcanoes in the world -” the majority along the Pacific Ring of Fire – and around 50 of these erupt each year.  An estimated 500 million people live near active volcanoes.  Historical time (or recorded history) is another timeshare for active.  The Catalogue of the Active Volcanoes of the World, published by the International Association of Volcanoes, uses this definition, by which there are more than 500 active volcanoes. [l O] However, the span of recorded history differs from region to region.
In China and the Mediterranean, it reaches back nearly 3,000 years, but in the Pacific Northwest of the United States and Canada, it reaches back less than 300 years, and in Hawaii and New Zealand, only around 200 years- Killable lava entering the sea. As of 2013, the following are considered Earth’s most active volcanoes:[1 2] Killable, the famous Hawaiian volcano, has been in continuous, effusive eruption for thirty years, and has the longest-observed lava lake. Mount Tent and nearby Storeroom, two Mediterranean volcanoes in “almost contain souse eruption” since antiquity.
Mount Yak’s, in Vaunt, has been erupting “nearly continuously” for over 800 years. The longest currently ongoing (but not necessarily continuous) volcanic eruptive phases 3] Mount Yak’s, 111 years Mount Tent, 109 years Storeroom, 1 08 years Santa Maria, 101 years Gangway, 94 years Other very active volcanoes include: Mount Marooning and its neighbor, Neuralgia, are Africans most active volcanoes Narration’s lava lake Piton De la Fairness, in Reunion, erupts frequently enough to be a tourist Errata Ale, in the Afar Triangle, has maintained a lava lake since at attraction. East 1906. Mount Rebus, in Antarctica, has maintained a lava lake since at least 1972. Mount Mermaid 01 Domino Lineage Embryo Arenas Volcano Papacy Ceaselessly Soaps Shovelful Extinct Perforated volcano, Alaska, in September 2007, after being thought extinct or over 10,000 years. Mount Iranian eruption in 1 994, in Limbo, Indonesia Extinct volcanoes are those that scientists consider unlikely to erupt again, because the volcano no longer has a magma supply.
Examples of extinct volcanoes are many volcanoes on the Hawaiian – Emperor easement chain in the Pacific Ocean, Honeywell, Shipwreck and the Suicidal volcano in the Netherlands. Edinburgh Castle in Scotland is famously located atop an extinct volcano. Otherwise, whether a volcano is truly extinct is often difficult to determine. Since “supernatural” calderas can have eruptive lifespan moieties measured in millions of years, a caldera that has not produced an eruption in tens of thousands of years is likely to be considered dormant instead of extinct.
Some paleontologists refer to extinct volcanoes as inactive, though the term is now more commonly used for dormant volcanoes once thought to be extinct. Dormant It is difficult to distinguish an extinct volcano from a dormant (inactive) one. Volcanoes are often considered to be extinct if there are no written records of its activity. Nevertheless, volcanoes may remain dormant for a long period Of time. For example, Yellowstone has a repose/recharge period of around 700,000 years, and Toby of around 380,000 years. 14] Vesuvius was described by Roman writers as having been covered with gardens and vineyards before its eruption of AD 79, which destroyed the towns of Herculean and Pompeii. Before its catastrophic eruption of 1991, Punctuation was an inconspicuous volcano, unknown to most people in the surrounding areas. Two other examples are the long-dormant Sufferer Hills volcano on the island of Montmartre, thought to be extinct before activity resumed in 1 995 ND Perforated Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BC and had long been thought to be extinct.