What Fundamental Parameters Determine the Vigor or Violence with Which a Volcano Erupts?

Volcanos

What fundamental parameters determine the vigor or violence with which a volcano erupts?

The parameters that determine the violence with which a volcano erupts are:

1. The magma's temperature.

2. The composition of the magma.

3. The amount of dissolved gases.

The magma, which is fluid molten rock is composed of gases and is part liquid and part solid. It comes from the mantle of the Earth's core which for the most part is solid because there is so much pressure that it usually can't melt. However, some times, circumstances such as convection of the rock up through the mantle or the melting rock at a subduction zone will create magma. The magma which can range in temperature from 1300 oF to 2400 oF, will then make its way up and out of the outer crust and collects in what are called magma chambers and when the pressure is great enough or a crack opens in the crust, the magma which is now lava spews out and forms a volcano. The temperature of magma determines the velocity and the lower the temperature the less velocity it has, thus a low temperature will create thicker lava and a smaller eruption, while a higher temperature will create thinner lava and a big eruption.

The amount of gases in a volcano are also a factor in the size of the eruption, if the magma has a lot of gas bubbles, it will have a more violent eruption. These gases vary due to the type of material that was melted during the formation of the magma. The most explosive volcanoes have high gas levels and high viscosity, but since each eruption has many stages to it, it is difficult to predict the destructiveness of a volcano.

If you were to visit a heretofore unknown volcano what specific data would you collect in order to predict the vigor or violence of subsequent eruptions.

The most important data I would want would be the history of eruptions from the volcano; this could help me to know what type of volcano it is. I would want to know if I was a Plinian Eruption (an extreme eruption like the one that buried Pompeii), a Hawaiian Eruption (a sluggish low level eruption) or a Strombolian Eruption (a lot of noise, but small amounts of lava).

Another piece of very important data would be the seismic activity of the volcano, which is the monitoring of the sounds in the earth. If an earthquake is about to happen, it can cause a volcano to erupt.

The vapors around a volcano are also important because as the magma rises, gases escape into the air and increases in gas measurements can predict eruptions.

4. Discuss the evidence for the sea floor spreading and continental drift concepts of the plate tectonic model.

The evidence for sea floor spreading comes from