EARTH SCIENCE
VOLCANOES
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Shield volcanoes, those with broad, gentle slopes.
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Volcanoes found in the ridge system.
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Very fluid magma, on the other hand, allows the expanding gases to move upward and escape easily from the vent.
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A notable example is the 1980 eruption of Mount St. Helens.
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Detailed explanation-1: -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.
Detailed explanation-2: -A high-speed blast leveled millions of trees and ripped soil from bedrock. The eruption fed a towering plume of ash for more than nine hours, and winds carried the ash hundreds of miles away. Lahars (volcanic mudflows) carried large boulders and logs, which destroyed forests, bridges, roads and buildings.
Detailed explanation-3: -Summary of Events A wave of decreasing pressure down the volcanic conduit to the subsurface magma reservoir, which then began to rise, form bubbles (degas), and erupt explosively, driving a 9-hour long Plinian eruption. Steam-blast eruption from summit crater of Mount St. Helens.
Detailed explanation-4: -Helens and other volcanoes in the Cascades arc due to subduction of the Juan de Fuca plate off the western coast of North America. Over its rich and complex 275, 000-year history, Mount St. Helens has produced both violent explosive eruptions of volcanic tephra and relatively quiet outpourings of lava.
Detailed explanation-5: -On the morning of May 18, 1980, after weeks of small tremors, a magnitude 5.1 earthquake shook beneath Mount St. Helens and triggered an enormous eruption.