GEOLOGY

Detailed explanation-1: -Mafic MagmaMafic magma has relatively low silica content, roughly 50%, and higher contents in iron and magnesium. This type of magma has a low gas content and low viscosity, or resistance to flow.

Detailed explanation-2: -Viscosity is the resistance to flow (opposite of fluidity). Viscosity depends on primarily on the composition of the magma, and temperature. Higher SiO2 (silica) content magmas have higher viscosity than lower SiO2 content magmas (viscosity increases with increasing SiO2 concentration in the magma).

Detailed explanation-3: -Magma that has a lower viscosity and lower silica content produces the volcanic rock called basalt and forms shield volcanoes. These basalt lava flows are what we find erupting out of the Kilauea volcano today in Hawaii.

Detailed explanation-4: -The magma that has the highest viscosity is rhyolitic magma. One of the main reasons for the high viscosity in rhyolitic magma is that it contains a large amount of silica. Silica is a mineral that is found in quartz and sandstone. Rhyolitic magma can be quite explosive when it comes to eruptions.

Detailed explanation-5: -Basaltic magma, having lower SiO2, is fairly fluid, but with increasing contents of SiO2, andesite, dacite, and rhyolite magmas become progressively more viscous. Because it is more difficult for dissolved gas to escape from more viscous magma, higher silica magmas generally erupt more explosively.