GEOLOGY

Detailed explanation-1: -A volcano erupts quietly if its magma is low in silica. Low-silica magma is thin and runny and flows easily. The gases in the magma bubble out gently.

Detailed explanation-2: -MAGMA COMPOSITION AND ROCK TYPES The magma types vary from mafic magmas, which have relatively low silica and high Fe and Mg contents, to felsic magmas, which have relatively high silica and low Fe and Mg contents.

Detailed explanation-3: -A quiet eruption of low-viscosity lava produces a wide, flat volcano called a shield volcano. If an eruption is entirely ash and cinders, the result will be a small, steep-sided volcano called a cinder cone.

Detailed explanation-4: -Magmas with high silica content have a high viscosity (resistance to flow) and are generally more explosive when eruptions occur. All magmas also contain some degree of trapped gasses (CO2 & H2O ). The more trapped gas the more violent the explosion. All magma that reaches the surface can be classified as Lava.