what role does pressure play in the formation of magma and volcanic eruptions?

Brief Explanations:

Pressure affects the melting - point of rocks. High pressure can prevent rocks from melting easily. During subduction, as rocks are pushed deeper into the Earth, increased pressure can lead to dehydration of minerals. This dehydration can lower the melting - point of surrounding rocks, facilitating magma formation. In volcanic eruptions, pressure build - up in the magma chamber due to the accumulation of magma and gases is crucial. When the pressure exceeds the strength of the overlying rock, it triggers an eruption.

Answer:

Pressure affects magma formation by influencing rock melting - points through processes like dehydration during subduction. It also plays a key role in triggering volcanic eruptions by building up in the magma chamber until it overcomes the strength of the overlying rock.