Final answer:
The violence or explosiveness of a volcanic eruption is determined by the type of magma, gas content, and volcano morphology.
Step-by-step explanation:
The factors that determine the violence or explosiveness of a volcanic eruption include:
- Type of magma: The composition and viscosity of the magma play a crucial role. Magma with a high silica content, such as andesitic or rhyolitic magma, tends to be more explosive compared to magma with a low silica content, like basaltic magma. High-silica magma has a higher gas content, which leads to more explosive eruptions.
- Gas content: The dissolved gases, mainly water vapor, carbon dioxide, and sulfur dioxide, in magma can greatly impact the explosiveness of an eruption. The higher the gas content, the more explosive the eruption. When the pressure in the volcano exceeds the strength of the surrounding rocks, the gases rapidly expand, leading to a violent eruption.
- Volcano morphology: The shape and structure of the volcano can influence the explosiveness of an eruption. A steep-sided volcano, like a stratovolcano, tends to trap gases and build up pressure, resulting in explosive eruptions. In contrast, a shield volcano, with gentle slopes, allows gases to escape more easily, resulting in less explosive eruptions.