Dynamics of Volcanic Eruptions

When a magma-filled fracture reaches the surface, a volcanic eruption occurs. In Chapters 5 and 7 we have discussed the conditions under which this may happen. Here, the focus is on the likely course of events once an eruption has started. Among the main questions facing scientists and civil authorities during a beginning eruption are: (1) What is the likely size or magnitude of the eruption? (2) What is its likely duration? (3) Is it going to be primarily effusive or explosive or both? All these questions ultimately relate to the hazards and associated risks posed by the particular volcano. For a more reliable assessment of the hazards associated with volcanoes, the frequencies and sizes of their eruptions need to be known and related to a general understanding of the dynamics of eruptions.