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In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens . Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent.
An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption. The volcanic materials form a vertical column or plume that may rise many kilometers into the air above the vent of the volcano. In the most explosive eruptions, the eruption column may rise over 40 km ...
A series of phreatic blasts occurred from the summit and escalated until a major explosive eruption took place on May 18, 1980, at 8:32 am. The eruption, which had a volcanic explosivity index of 5, was the first to occur in the contiguous United States since the much smaller 1915 eruption of Lassen Peak in California. [2]
A.D. 79: Mount Vesuvius, Italy. Mount Vesuvius has erupted eight times in the last 17,000 years, most recently in 1944, but the big one was in A.D. 17. One of the most violent eruptions in history ...
Some of the eruptive structures formed during volcanic activity (counterclockwise): a Plinian eruption column, Hawaiian pahoehoe flows, and a lava arc from a Strombolian eruption. Several types of volcanic eruptions—during which material is expelled from a volcanic vent or fissure—have been distinguished by volcanologists.
The eruption sent dark ash plumes of up to 8 km (five miles) billowing into the sky and ash fall was recorded even at the Argyle International Airport, according to St. Vincent’s National ...
The caldera is the enormous volcanic crater left from the last time Yellowstone experienced a giant eruption, 640,000 years ago. It covers an area about 30 by 45 miles .
Hyalotuff is a type of rock formed by the explosive fragmentation of glass during phreatomagmatic eruptions at shallow water depths (or within aquifers). Hyalotuffs have a layered nature that is considered to be a result of dampened oscillation in discharge rate, with a period of several minutes. [3]