ERUPTION CHARACTERISTICS
All records about volcanic eruptions present a more or less similar chart, which is entered to the occurrence of some premonitory phenomenon such as smoke emanation in a crater that seemed inactive or the apparition of a new crater. This can last several days, weeks or even years, until a series of quakes and underground noises precede the exit of ashes and lava, which flows at 5 to 100 km/h, depending on the geographic slope, usually following the ravines in the area and leading to rivers or lakes. The eruptive phase has lasted from a few weeks, to five or more years.
Damage as far as human lives, therefore, has not been as tragic as in the case of earthquakes or tsunamis, since the population usually has enough time to go to a safe place. Depending on the season in which the eruption takes place, accelerated thawing and avalanches may be produces, which are what has produced more victims than lava itself.
Material damage is usually plentiful, in agriculture as well as livestock. Livestock can suffer great mortality by failing to flee from the lava or because the ash rain covers the earth, causing asphyxia or inability to get food.
How can I protect myself from a volcanic eruption?
A volcano is a mountain that opens at the bottom to a deposit of melted rock under the surface of the earth. Unlike most mountains, that are pushed from below, volcanoes are built by an accumulation of their own eruptive products. When the gas pressure inside a melted rock is too high, an eruption is produced. Eruptions may be calm or explosive. Lava flow, landscape crushing, poisonous gasses and flying rocks and ashes are common incidents during an eruption.
Due to its intense heat, lava flow is a great fire hazard. Lava flows destroy everything in their path, but most move so slowly that they provide enough time to leave the area.
Fresh volcanic ash, made by pulverized rock, may be abrasive, acid, sandy, gassy and fragrant. Volcanic ash may affect people hundreds of miles from a volcano.
Volcanic explosions may be directed sideways, known as “lateral explosions”, may shoot large pieces of rock at high speeds through several miles. These explosions can kill by impact, puncture or heat. Entire forests have been knocked down.
Volcanic eruptions can come along other natural catastrophes, including earthquakes, mudslides and flash floods of rocks and landslides, acid rain, fires and special tsunami conditions.
Active volcanoes in the United States are mainly in Hawaii, Alaska and Northeastern Pacific. Active volcanoes of the Cascade Mountain Range in California, Oregon and Washington have created problems recently. The danger zone around a volcano area covers approximately a 20 mile ratio. In some areas the danger can exist at 100 miles or more from a volcano, leaving Montana and Wyoming in a danger situation.
