GEOLOGY

Detailed explanation-1: -Basaltic composition magmas are the most common effusive eruptions because they are not water saturated and have low viscosity.

Detailed explanation-2: -So, mafic lavas are hot, low in silica and volatiles, and have relatively low viscosity. They flow easily outward from the vent (where it comes out of the ground), and may travel great distances before completely solidifying. Felsic lavas are not as hot, high in silica and volatiles, and have a high viscosity.

Detailed explanation-3: -Differences in a magma’s viscosity will determine the shape a volcano takes. High-silica (basalt) magma has a much lower viscosity. It flows much easier and over longer distances. As low-silica magma cools, it hardens to rock, adding a new thin layer of rock to the volcano.

Detailed explanation-4: -Describes magma that contains lower amounts of silica and is generally less viscous and less gas-rich than silicic magma. Tends to erupt effusively, as lava flows.