Sample Geology Paper on Volcanoes


  1. Describe two factors that control the violence or style of a volcanic eruption?

The factors that affect or control the style of volcanic eruption include the composition of the magma, temperature and the dissolved gasses in the magma. The effect of temperature on viscosity leads to enhanced action and therefore if the temperature is controlled, then the eruption could not be violent. At the same time, if the composition consists of materials that are resistant to flow, eruption will be less violent.

  1. Describe at least two ways that victims of the CE 79 eruption of Mt Vesuvius were


As the mountain erupted, molten rock (magma) flew smoothly covering all that it could find along the way there by killing the victims. At the same time, the victims could have been killed by mudslide that were set off by the eruption and tremors that engulfed Herculaneum.

  1. What is the difference between a shield volcano and a stratavolcano?

A shield volcano has a long gentle slope that is caused by highly fluid lava flow of ballast after it has erupted as compared to the strato volcano which is steep sided as a result of more vicious explosive lava. The strata volcano has a higher proportion of silica and more gas comparatively in the magma than the shield volcano

  1. What is a caldera? Name at least two famous calderas in the USA.

A caldera is a depression that is created after a volcano releases most of its contents the (the magma chamber) in an eruption that is explosive and in the absence of any structural support below the land thereby causing the vent of the erupting volcano to collapse inwardly thereby creating a bow shaped thing/caldera. It is different from a crate in that a crate forms as a result of outward explosion of rocks and other materials from a volcanic eruption and not inward curve as in a caldera.

An example of a caldera in the US is the Crater Lake which is the deepest in the US. The Yellowstone caldera located in WyomingState is another type of shield volcano

  1. List three ways that, solid hot rock can be melted to produce liquid magma.

One of the ways a solid hot rock can be melted to produce liquid magma is by heating the rock at temperatures between 800 and 1200 degrees Celsius. If water is added to convergent boundaries around the subduction zones, rocks may melt at lower temperatures.

Still, transfer of heat at convergent boundaries where the tectonic plates are crushing together would lead to magma formation. At the same time, pressure decrease may lead to the formation of liquid magma at divergent boundaries (decompressing melting at divergent boundaries separating the tectonic plates).