GEOLOGY

Detailed explanation-1: -This is the type of volcano many people think of when they imagine volcanoes. These volcanoes have broad bases and sides that get steeper and steeper as you get closer to the top. They frequently have a large crater at the top created during its last eruption.

Detailed explanation-2: -Because the composition of magma is different in different volcanoes, the properties of the lava are different. In effusive eruptions, lava flows are relatively calm and do not explode out of the volcano.

Detailed explanation-3: -Stratovolcanoes are more likely to produce explosive eruptions due to gas building up in the viscous magma. Andesite (named after the Andes Mountains), is perhaps the most common rock type of stratovolcanoes, but stratovolcanoes also erupt a wide range of different rocks in different tectonic settings.

Detailed explanation-4: -Composite volcanoes are built up by successive eruptions of domes, lava flows and pyroclastic flows, but also can experience large blasts that destroy large areas of their summits, such as the May 1980 explosion and landslide at Mount St. Helens. Landslides may occur during eruptions or at other times.

Detailed explanation-5: -As a general rule, therefore, nonexplosive eruptions are typical of basaltic-to-andesitic magmas which have low viscosities and low gas contents, whereas explosive eruptions are typical of andesitic-to-rhyolitic magmas which have high viscosities and high gas contents.