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Dangers of Volcanic Eruptions
Volcanoes are of several types and are found around the world
Volcanoes are dangerous no matter where they are
Volcanoes for all their beauty when they lie dormant or when they display a great show of pyrotechnics can be dangerous in many ways. May people live in the shadow of volcanoes have paid with their lives when the volcano exploded into life. There have been many instances in the past where volcanoes have created havoc in nature and in the lives of people. Among these destructive forces are super-heated gases, discharges of carbon dioxide or hydrogen sulfide, snow and glacial melts and floods, flows of pyroclastic ashes, lava bombs, flowing lava and associated wile-fires and tsunamis. Sometimes the eruption is so severe as to cause global weather changes after the eruption that affects all of nature and civilization. The most dangerous volcanoes are the ash producing type as opposed to the ones producing lava flows. Those who live in the shadow of volcanoes should to be prepared to move when the volcano is showing signs of life. Often there is plenty of warning if one knows what to look for.
The eruption of Mount St. Helens in Washington State in 1980 was a case in point, though it was not a super eruption or a major one at that. Before the main event, which occurred very suddenly, there were harmonic tremors and steam venting for two months. Then at 8:32, local time on May 18th, 1980, the north slope collapsed and exploded with great ferocity, sending an upward and sideways venting mass of ash over great distances. Those who were in the way of the super-heated pyroclastic flow were incinerated and killed. Otherwise, ash took its toll on people breathing and the air intakes of automobile and aircraft engines. The snow on the peak melted and flowed in raging floods down the streams and rivers along the slopes of the volcano. Trees by the thousands were swept up by the flood waters and all this mass took out bridges lower down. The column of ash reached into the stratosphere and rained ash down in eastern Washington and in eleven states. Hundreds of square miles of forest and cottages were leveled. 57 people died and many more injured. Luckily, the volcano was in a mostly wild region. Were it located in populated areas like Vesuvius, the damage to life and property would have been far greater.
In 70 AD, Vesuvius erupted and killed most of the inhabitants in Pompeii and Herculaneum. So much ash was deposited that people were buried alive and petrified to be uncovered almost 2,000 years later. In some areas, the ash deposit was up to fifty feet. Many people who attempted to flee by sea, were flashed burned to death in a pyroclastic flow when the Plinian phase of the eruption collapsed and the ash descended down the flanks of the volcano and out to the sea. Again, there was plenty of warning, but folks hoped for the best and stayed put, even during the early stages of the eruption when escape was still possible. Pliny the younger recorded much of went on as hos father died attempting to rescue others by sea.
Tsunamis unleashed by Krakatau in 1883 killed 30,000 people on shorelines surrounding the Sudra Straight in the region of Java. In addition, the copious amount of ash produced, reduced global temperatures for a few years, producing years with no summers and coloring the sunsets that are recorded in Turner paintings in Great Britain. Years without summers means that there is little to harvest and masses of animals and people go hungry. Krakatau has always been a problematic volcano and is now thought to be responsible for the change of history that began in the mid sixth century.
This just in from Japan, MArch 13, 2011
Less than a century earlier, Tambora erupted with similar results that lead to food shortages after the 1815 eruption. This then led to unrest in Europe for decades into the 1840s and helped to lay the foundations of Communist theory.
Sometimes an eruption is preceded by an outflow of great quantities of carbon dioxide. Carbon dioxide is heavier than air and hugs the ground. As a result, anything caught in the outflow from the volcano is asphyxiated and dies. In central Africa, such an even occurred that resulted in a mass die off of animal populations and people. Little ash or lava was ever produced.
Lava flow has the danger of creating fire storms, especially if the flow is a large one, such as seen in Hawaii or Iceland at various times. Usually there is enough time to get out of the way of such events. Lava fountains can be spectacular, but when mixed with gas, there can be lava bombs that can be projected over considerable distances, causing spot fires wherever they land and injury or death to anyone they hit.
The recent April 20th, 2010 eruption of the Eyjafjallajokull volcano in Iceland caused nearly $2 billion in losses to European airlines as they shut down for over a week due to ash. This inconvenienced millions of travelers. In Iceland, the melting glaciers produced a lot of steam, ash and flood waters. Locally, only 70 people were evacuated as this volcano is in an isolated region. However, the ash cloud had wide ranging effects that will be felt for years. The danger of the ash as that it clogs and stalls engines, especially jet turbines, creating a potential for airline crashes and mass death.
Sometimes a new volcano can “pop up” seeming out from under ones feet just like in the movie scenario where a volcano is born in Los Angeles out of the Le Brea tar pit. “On the afternoon of February 20, 1943, Dionisio Pulido, a farmer in the Mexican state of Michoacán, was readying his fields for spring sowing when the ground nearby opened in a fissure about 150 fee long. "I then felt a thunder," he recalled later, "the trees trembled, and is was then I saw how, in the hole, the ground swelled and raised itself 2 or 21/2 meters high, and a kind of smoke or fine dust–gray, like ashes–began to rise, with a hiss or whistle, loud and continuous; and there was a smell of sulfur. I then became greatly frightened and tried to help unyoke one of the ox teams”.
Virtually under the farmer's feet, a volcano was being born. Pulido and the handful of other witnesses fled. By the next morning, when he returned, the cone had grown to a height of 30 feet and was "hurling out rocks with great violence." During the day, the come grew another 120 feet. That night, incandescent bombs blew more than 1,000 feet up into the darkness, and a slag like mass of lava rolled over Pulido's cornfields."(1)
The Earth’s geomagnetic field is currently undergoing changes which suggests changes going on below us. In addition to changing magnetic fields, we can expects some active volcanoes to go dormant, some dormant ones to suddenly come back to life, and new ones springing up from under our feet with all the dangers that come from volcanic activity.