Question

First person to answer get brainliest. (if its right)

1) When does an eruption begin?

2) What determines if an eruption will be explosive or nonexplosive? Explain.

3) What is viscosity? What determines a magma’s viscosity? Explain.

4) What causes lava to be fluid and runny? What causes lava to erupt as pyroclasts?

Answer 1

Answer:

1) Volcanoes erupt when molten rock called magma rises to the surface. Magma is formed when the earth's mantle melts. Melting may happen where tectonic plates are pulling apart or where one plate is pushed down under another. Magma is lighter than rock so rises towards the Earth's surface.

2) The amount of dissolved gas in the magma provides the driving force for explosive eruptions. The viscosity of the magma, however, is also an important factor in determining whether an eruption will be explosive or nonexplosive.

3) Viscosity is the resistance to flow (opposite of fluidity). Viscosity depends on primarily on the composition of the magma, and temperature. Higher SiO2 (silica) content magmas have higher viscosity than lower SiO2 content magmas (viscosity increases with increasing SiO2 concentration in the magma).