What does a volcanic eruption do?

Answer 1

The effects vary depending on the kind of eruption. In an effusive eruption lava essentially oozes out of a vent or fissure. The lava, which is generally runny, basaltic lava then flows downhill. Such eruptions mean the magma has a low gas content Lava flows of more viscous lavas can occur as well. These flows do not look like the typical lava flow. Then there are various types of explosive eruptions. Fire fountain eruptions are somewhat explosive and usually involve basaltic lava. In these cases lava fountains into the air, sometimes resulting in lava flows. More viscous lavas with higher gas content can result in the formation of chunks of rock called volcanic bombs. More explosive eruptions are associated with more viscous lavas such as andesite, dacite, and rhyolite. These eruptions send up clouds or columns of volcanic ash. These are the most dangerous eruptions. The ash, which consists of tiny pieces of glass, is harmful to the lungs and can contain toxic substances. Some material races down the slopes in the form of pyroclastic flows, fast moving avalanches of superheated ash, pumice, and gas that destroy everything in their path and create unsurvivable conditions. Large explosive eruptions can destroy vast areas and bury nearby locations deep in ash and pyroclastic deposits. Gasses released by such eruptions can lower global temperatures. The largest explosive eruptions cause the magma chamber to partially empty, causing the volcano above to collapse into a caldera. Looking at ash deposits scientists have identified a number of super eruptions far larger than any that have occurred in recorded history. Such eruptions dramatically affect climate and cover vast regions with ash.
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