GEOLOGY

Detailed explanation-1: -Acid magmas are more viscous than basic magmas because they are richer in silica. Gases can not escape as efficiently from acid magmas and so these tend to be associated with more violent, explosive events and the volcanoes they give rise to tend to be made more of pyroclastic deposits.

Detailed explanation-2: -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 Pelean eruption is associated with explosive outbursts that generate pyroclastic flows, dense mixtures of hot volcanic fragments and gas described in the section Lava, gas, and other hazards.

Detailed explanation-4: -Effusive eruptions If a magma has low viscosity (it is runny), gas can escape easily, so when the magma erupts at the surface it forms lava flows. These eruptions are (relatively!) gentle, effusive eruptions.