Final answer:
Viscosity is a property that measures the resistance to flow of fluids. In volcanic eruptions, viscosity determines whether the eruption will be explosive or effusive.
Step-by-step explanation:
Viscosity is a property of fluids that refers to their resistance to flow. It measures how easily a liquid can flow, with low viscosity liquids flowing quickly and easily, while high viscosity liquids flow slowly and stick to surfaces. In the context of volcanic eruptions, viscosity plays a crucial role in determining the eruptive style of a volcano.
Volcanic eruptions can be explosive or effusive, depending on the viscosity of the magma. If the magma is highly viscous, it traps gases within it, creating a buildup of pressure. When this pressure is released explosively, it leads to explosive eruptions with ash, pyroclastic flows, and volcanic bombs. On the other hand, if the magma is low in viscosity, it allows gases to escape more easily, resulting in effusive eruptions with relatively gentle lava flows.