Does the rock basalt have gases trapped within?
Almost all types of rocks that rise to the surface contain gas in it to some degree. This is why the rocks rise to the surface. Density difference’s, usually gas inside the rock causes the rock to be less dense from the surrounding rock therefore it rises and meets the surfaces and erupts. Basalt has a very relatively low gas concentration within it compared to Andesite or Rhyolite. This is why basalt has pretty quiet eruptions along with other factors such as Silica content and Viscosity.
