"The magma causes the water to be quickly converted into gaseous state (steam), causing steam explosions and tephra fall (ash). There is considerable uncertainty regarding the amount of gases from ...

The Ash3d tephra model, co-developed by Larry Mastin ... Yellowstone have been lava flows with no significant amounts of ash ...

Eruptions of steam, ash, and tephra continued until June 1917 ... The volcanic areas are best visited in summer and fall. Heavy snows close most of the main road in winter. But visitors still ...