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1. What lessons can we derive from these volcanic eruptions?
Volcanoes are mystical in their own right, and a volcano eruption is a splendid and breathtaking sight to behold. However, one must also be reminded of the fact that volcano eruptions are classified as ‘natural hazards’. Active volcanoes are dangerous, and spectacularly destructive. Volcanic eruptions bring disastrous effects and great harm on both humans and the physical landscape. However: volcanoes are not entirely harmful. They also bring beneficial effects when they erupt.
First, here is a brief overview of different types of volcanic eruptions: lava eruptions and pyroclastic eruptions. The two stated above can be further divided into sub-categories. For lava eruptions, there are Icelandic activity and Hawaiian eruptions. For pyroclastic eruptions, there are Strombolian, Vulcanian, Vesuvian, Plinian and many others (all the names are derived from the names of actual volcanoes). Of the two, pyroclastic eruptions are believed to be the more devastating type.
When a pyroclastic eruption occurs, showers of burning hot rock fragments, steam, mud and ashes spew out. These are aptly dubbed ‘pyroclasts’. The pyroclasts are hurled to a great height, and fall over the surroundings, burying whole towns and whatever is unfortunate to be in their path. Molten magma is spewed out next; able to reach over 450 m in the air, as in the 1983 eruption at Kilauea. The fantastic fire mountains are startling evidence of the immense pressure and heat in the molten fathoms.
This can be seen in the eruption of 1631, which made Vesuvius a household name. The twin cities of Pompeii and Herculaneum near Naples, were buried alone by mud, ashes and fragments of rock of borne by steam and other gases. All in all, there were six flows. The first flow reached Herculaneum, killing all in its path. The third one reached the outer walls of Pompeii and buried Herculaneum, and the fourth one asphyxiated Pompeii. The final one buried it. The consecutive surges of pyroclasts darkened the sky. At least 2000 died in Pompeii, while most of the residents in Herculaneum probably escaped.
People buried by the eruption of Vesuvius
The 1815 eruption of Tambora, Indonesia, killed 12,000 people by direct effects and up to 70,000 died of famine following the spoliation of land and crops. The 1902 eruption of Mt Pelee killed 30,000 people in a minute and left only two alive. In the same year, the eruption of La Soufriere took 2000 lives and caused the extinction of the Caribs, the original inhabitants of the island when Columbus discovered it. These eruptions are just various examples of just how destructive volcanoes can be.
More recent eruptions include the Mount Merapi eruption. By early May, active lava flows had begun. Some 17,000 people were evacuated from the area when lava flows begun to be constant on May 11. On May 27 2006, a 6.2 magnitude earthquake struck roughly 30 miles southwest of Merapi, killing 5,000 and leaving at least 200,000 people homeless in the Yogyakarta region, as lava and superheated clouds of gas poured repeatedly down the upper slopes.
Merapi in 2006
Another recent eruption was the Mayon Volcano in the Philippines, on 17 July 2006. About 30,000 Filipinos have been forced to flee as the Mayon Volcano erupted, spewing out rocks the size of cars and sending clouds of ash thousands of metres into the air.
Deadly ash and rock race down the mountain side
The very hot and smoking pyroclastic materials flowing down from the peak of Mayon Volcano have enormously amassed to as high as a 4-storey building at the southern slopes
Explosive eruptions at the coastline and in the sea create massive sea waves called tsunamis. During the 1883 eruption of Krakatoa in Indonesia, a tsunami created rose to nearly 40 m, sweeping over hundreds of settlements and drowning more than 30,000 people in Sumatra and Java.
The large quantities of volcanic ash and dust thrown out during an eruption also pollute the environment, as the ash and dust are believed to remain in the atmosphere for months, or years. They damage the respiratory systems of both people and livestock, and contaminate water sources and vegetation. When the copious amounts of steam ejected during an eruption condense, heavy rain and flooding occurs. Scientists believe the large quantities of ejected sulphur particles (during the 1991 eruption of Mount Pinatubo in the Philippines) that remain in the atmosphere for years potentially increase ozone losses in the stratosphere.
Copious amounts of ash thrown out during Mount Pinatubo eruption
Despite the danger of volcanoes, there are nevertheless many benefits to be derived from volcanic activity. In contrast to the paragraph above, the 1815 eruption of Tambora, Indonesia which caused more than 20 cubic miles of debris to be blown into the sky hung in the upper atmosphere, cooling the planet by shading it from the sun’s radiation.
Benefits to farming
Lava that is spewed out, with other volcanic materials, can be weathered to form fertile soil suitable for farming. Farmers thus benefit, being able to reap rich harvests. The slopes of Gunung Merapi in Central Java, Indonesia are terraced for rice cultivation because the volcanic material enriches the soil with minerals, making it fertile.
Terracing on slopes of Gunung Merapi
Volcanic areas also appeal to many tourists, making the tourism industry in those countries a valuable source of revenue, as the areas can be turned into tourist destinations. Every year, tourists flock to see the glowing lavas of Mount Etna in Italy, the symmetrical snow-capped Mount Fuji in Japan and the gently sloping shield volcanoes formed by hot spots in Hawaii.
Shield volcanoes in Hawaii
Geothermal energy can be tapped in volcanic areas. The heat beneath the Earth’s surface is used to generate electricity. Already, there are geothermal plants in places such as Mexico. In the future, as sources of energy become increasingly limited, geothermal energy will prove to be a valuable source of ‘clean’ energy.
A geothermal plant in Reykjavik, Iceland
It would be greatly unjust to have the erroneous notion that volcanic eruptions bring nothing but harm and devastation to people. Volcanic eruptions can be useful as well. Hopefully in the future, volcanologists will derive various methods of predicting volcanic eruptions so that there will not be so many fatalities and volcanic eruptions will be purely beneficial.
Posted by GP Four