GEOLOGY

EARTH SCIENCE

VOLCANOES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the main idea of the entire passage?
A
Volcanoes are all the same inside.
B
Volcanoes are found all over the world.
C
Volcanic eruptions are the reason islands form.
D
Volcanic eruptions are a powerful force of nature.
Explanation: 

Detailed explanation-1: -A volcanic eruption is when lava and gas are released from a volcano-sometimes explosively. The most dangerous type of eruption is called a ‘glowing avalanche’ which is when freshly erupted magma flows down the sides of a volcano. They can travel quickly and reach temperatures of up to 1, 200 degrees Fahrenheit.

Detailed explanation-2: -The most violent eruption registered in history was that in the La Garita Caldera in the United States. It occurred 2.1 million years ago and formed a 35 x 75 km crater, drastically changing the climate on Earth. Fortunately, these eruptions are rare: they occur every 50, 000 or 100, 000 years.

Detailed explanation-3: -Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth’s surface.

Detailed explanation-4: -When enough magma builds up in the magma chamber, it forces its way up to the surface and erupts, often causing volcanic eruptions. In the ocean, volcanoes erupt along cracks that are opened in the ocean floor by the spreading of two plates called a mid-ocean ridge .

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