Volcanic eruptions involve the incursion of liquid magma into a physical environment, and the effects include major transformations, ranging from the formation of new land to the destruction of the viability of an existing environment. Just one example of the creation of new land comes from the Hawaiian Islands, which appeared as magma cooled into land after eruptions.
As lava flows across the ground in the wake of a volcanic eruption, any existing plant life is at risk of immediate destruction. When lava mixes in with melting snow or rain water, the flow speeds up, and the environmental effects accelerate as well, because the destructive effects of the lava largely remain, but the spread is generally wider and takes place more quickly.
An example of this took place in Montserrat when Chances Peak entered a phase of eruption between 1995 and 2000. In 1995, the mountain began giving off signs of coming activity through eruptions of ash and dust. The most intense eruptions took place in 1997, and 11,000 people were evacuated to the northern end of the island as well as to other islands.
The result of the eruptions involved the covering of the capital in mud and ash, and the destruction of more than a dozen settlements which have been rendered uninhabitable.