Final answer:
Effusive eruptions produce steady lava flows with relatively manageable hazards, such as property damage, while explosive eruptions generate violent blasts of ash and gas with hazards like pyroclastic flows, ash fall, and lahars, posing significant threats to society.
Step-by-step explanation:
Difference Between Effusive and Explosive Eruptions
The difference between effusive and explosive eruptions lies in their eruptive behavior, products, and the hazards they pose. Effusive eruptions involve the flow of lava onto the surface, forming flows which may cover large areas but generally move slowly enough to allow people to move out of their path. The primary hazards from effusive eruptions include burns from lava, forest fires, and property damage. In contrast, explosive eruptions blast ash, lapilli, and volcanic blocks high into the air and can devastate areas through pyroclastic flows, tephra fall, and lahars. These eruptions can collapse roofs, bury cities under ash, and even affect global climate. Explosive eruptions pose a significant threat to life and infrastructure, especially in densely populated regions like Sumatra and Java in Indonesia.
Explosive eruptions result from the rapid release of gas from magma, often caused by the cooling and crystallization of magma, which increases the magma's viscosity, trapping more gases within. This can lead to a pressure build-up that is suddenly released in a violent explosion. In contrast, effusive eruptions generally occur when magma is low in silica, making it less viscous and allowing gas to escape more easily, resulting in a steady, non-explosive flow of lava. The hazards associated with these eruptions vary, with explosive eruptions being potentially much more deadly and damaging, as witnessed in historical eruptions like that of Mount Vesuvius in 79 AD which buried Pompeii and Herculaneum.