Johnson Hi Johnson, Relative quiet and benign volcanic eruptions occur at basaltic volcanoes, such as Kilauea, Hawaii. Such volcanoes do not explode because the magma has a low amount of dissolved gas and because the small amount of gas that does exist can move freely through the very fluid magma. Explosve volcanoes, such as Mount St. Helens and Pinatubo, explode because their magma is very viscous and gas cannot escape readily.
Pressure builds up in the magma and an explosion results.