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Volcanoes and Earthquakes

I need help with the following questions;

How do different categories of volcanoes form?

What is an earthquake? What causes earthquakes?

Why is most of the volcanic activity in the United States located in the Pacific Northwest region?

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How do different categories of volcanoes form?

There are four major types of volcanoes: cinder cones, composite volcanoes, shield volcanoes and lava domes.

Cinder cones are typically referred to as the simplest type of volcano. They develop from particles and blobs of lava that are ejected from one single vent. The lava is usually gaseous and is blown into the air in a violent explosion. Such explosive eruptions are caused by gas rapidly expanding and escaping from molten lava that formed into cinders. It then breaks into small fragments that solidify, accumulating around the vent as cinders (Nakamura, 1976). This forms a circular or oval cone depending on the vent and explosion. As cinders fall back onto the vent they create a funnel-shaped crater at the top of the cone (Nakamura, 1976) Most cinder cones have a bowl-shapes crater and are shorter, rising only to about a thousand feet maximum above the landscape (Nakamura, 1976).

Composite volcanoes are sometimes referred to as stratovolcanoes and are typically steep, symmetrical cones that are relatively large compared to other volcanoes. They are composed of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and can rise up to 8000 feet above their base (Gudmundsson, 1992). A composite volcano originates from magma rising up from the conduit and erupting at the earth's surface to form a ...

Solution Summary

Volcanoes and earthquakes categories are examined. Why most volcanic activity in the United States is located in the Pacific Northwest region is determined.