In Portland, we live only 80 kilometers from an active volcano; Mount St. It is important to know how an eruption from a volcano could affect our daily lives. Since the eruption in May of 1980 of Mount St. Helens, geologists have come to a better understanding of both the mechanics of volcanoes and the dangers they present to the environment and communities. This better understanding will in the future help public authorities take action to lessen the consequences of a major eruption. In this paper, I will explain the process that produces volcanic eruptions and the hazards they present. I will also explore how government and other authorities have taken action in past volcanic eruptions to prevent or lessen the consequences of these events.
Volcanoes and What they Produce.
The term volcano refers to a mountain or hill formed by the accumulation of materials erupted through one or more openings in the earth's surface and the openings themselves (Encarta). Volcanic activity can last from thousands of years to just a few weeks, but eventually all volcanoes will become extinct (Zeilinga de Boer, 7).
When volcanoes erupt they produce three types of material; lava, gases and tephra which are all produced from magma (molten rock). The type and amount of the material produced depends on the composition of magma. If magma is fluid it can flow rapidly down the mountainside, while lava that is stickier moves much slower but can produce an explosive eruption (Ruzicka). The gases released from volcanic eruptions, consists mostly of water vapor but also include carbon dioxide, sulfur dioxide and other gases. Tephra, also know as pyroclastic material, is made of rock fragments coming from either solidified pieces of magma or parts of the pre-existing rock torn from the volcano. The dense pyroclastic material; which is fresh magma, pumice or volcanic ash travels along the ground at fast speeds during explosive eruptions.
