Technology

Volcanic eruption is a natural phenomenon that can cause a great deal of damage to properties and loss of lives. Lava flows are commonly perceived as the primary hazard during a volcanic eruption. However, this belief has been proven to be false. There are more dangerous hazards that must be observed during a volcanic eruption, and some of these are volcanic earthquakes, pyroclastic surges and flows and lahars.

Volcanic earthquakes occur when there is a great stress and pressure changes in the ground due to the injection of magma. These types of earthquakes can result to ground cracks, ground deformation and destruction of buildings and houses around the volcano. However, the most alarming effects of the earthquakes are landslides and tsunamis. Landslide can happen when there is a great mass movement from a higher ground to a lower one. Tsunamis, on the other hand, are large waves that can cause large damage, especially to people living near the coastal area. To show the destructive powers of volcanoes, Krakataus explosion in 1883 created waves that is as high as 35 meters. The waves were the main cause of death, killing around 30000 people.

Fast and unstable low density flows made out of pyroclastic materials are called pyroclastic surges. These surges are hot enough to burn houses, animals, vegetation and, when caught, even human skin. Pyroclastic surges killed 30000 people when Mount Pelee exploded in 1902. On the other hand, pyroclastic flows are hot fluidized masses of rock fragments and denser than pyroclastic surges. Pyroclastic surges and flows also emit gases that can result to ash rainfalls and asphyxiate people.

Lastly, one of the most detrimental hazards of a volcanic eruption is lahars. Lahars are similar to pyroclastic flows except for it contains more water. They can be formed when rainfall on loose materials like ashes and when pyroclastic flow dilutes with some bodies of water like rivers. Like pyroclastic flows and surges, lahars are also turbulent and can extend its damage up to hundreds of kilometres from the volcano (Riley, 2010).

Pyroclastic flows and lahars are so far deemed to be the most dangerous volcanic hazards. Direct results from a volcanic eruption like pyroclastic surges and flows, lava flows and earthquakes can produce damages on ground structures and can claim human lives. Conversely, an indirect result from the explosion like lahars has been proven to be as vicious as the direct results.

Catastrophism and uniformitarianism are the two of the most common views and arguments of scientists on how the Earths geological structure evolved through time. Catastrophism explains the geological changes in Earths physical structure as an abrupt, violent and short-term process. On the other hand, uniformitarianism describes these changes as a long and gradual process.

The two concepts differ in many aspects. Followers of catastrophism believe that the causes of physical changes in the environment are a series of violent events that happened so fast and do not conform to a particular pattern. The meteor that killed the dinosaurs millions of years ago is an example of these events. On the other hand, uniformitarianist believed that the events that causes changes on the environment reoccurs at an exact interval and that these events have the same rate. Because it is assumed that these events occur at the same rate, it is possible, according to them, to determine the past events using the current events experienced.

Most geologists accepted the concept of uniformitarianism. According to them, it is the closest thing to reality. It also appeared in most of the books on earth science. Geologist also found out that the sudden major events of extinction are not really sudden. Careful study of the data reveals that these events have a reoccurrence period of about 30 million years (Hancock, et al, 2000).