GEOLOGY

Detailed explanation-1: -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.

Detailed explanation-2: -Volcanic eruptions can be explosive, sending ash, gas and lava high up into the atmosphere, or the magma can form lava flows, known as effusive eruptions. Whether an eruption is explosive or effusive largely depends upon the amount of gas in the magma.

Detailed explanation-3: -Explosive eruptions are favored by high gas content & high viscosity magmas (andesitic to rhyolitic magmas). The explosive bursting of bubbles fragments the magma into clots of liquid that cool as they fall through the air.

Detailed explanation-4: -The amount of water vapor and other gases present is one factor that determines whether a volcanic eruption will be quiet or explosive.-Gases can be trapped in magma by pressure of surrounding magma and rock; eventually they cause an explosive eruption.