Microscopic 'seeds' in magma dictate volcanic danger: Study

A new study suggested microscopic crystal "seeds" in magma dictate nature of volcanic eruptions. It found when magma undergoes superheating before ascent, crystals dissolve. Superheated magma delays crystal formation for eight hours compared to 20 minutes in non-superheated magma. Superheated magma thus increases likelihood of explosive lava fountains while crystals result in slower lava flows.