What are the primary factors that determine whether a volcano erupts explosively or relatively quietly?

The primary factors that determine whether a volcano will erupt explosively or relatively quietly are:

i.The density of magma present

ii.The pressure exerted  by the gases existing in the magma

iii.Addition of a freshly formed magma into a previously filled magma chamber

iv.Viscosity

v.Content of gases present in the  magma

Further Explanations:

The volcanoes are the ruptures present in the crust of a planetary body, such as Earth from where hot lava, volcanic dust, and other gases to outflow from the magma chamber to the surface. Earth's volcanic eruption occurs because its crust has fragmented into seven rigid tectonic plates that float on a warmer, soft layer of its mantle. Volcanoes erupt when molten rock upswings to the surface from cracks and faults present on the exterior of the earth. Magma formed from the melting of the mantle erupts through openings in the earth's crust a fore flowing on the surface in the form of lava. If magma is thick, gas bubbles can’t easily escape and pressure builds up.

There are many factors that determine the intensity of the volcanic eruption. Viscosity and the gaseous content of the magma play a very important role in determining the intensity of the blast and the quantity of the magma erupted.

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Answer Details

Grade: High School

Subject: Geography

Chapter: Volcanoes

Keywords:

volcanoes, planetary, body, hot lava, volcanic dust, other gases, tectonic plates, warmer, soft layer, intensity, Magma, lava

it is b that is the answer.