Effects of Volcanoes
Volcanoes present both positive and negative effects to both the environment and people. Avalanches of rock and ice are also common on active volcanoes. They may occur with or without an eruption. Those without an eruption are often triggered eathquakes, by weakening of rock into clay by hydrothermal activity, or by heavy rainfall or snowfall. Those associated with eruptions are sometimes caused by oversteepening of a volcano’s flank by intrusion of a shallow body of magma within or just beneath the volcanic cone. A caldera collapse that is in part or entirely submarine usually generates a tsunami. The larger and more rapid the collapse, the larger the tsunami. Tsunamis also can be caused by avalanches or large pyroclastic flows rapidly entering the sea on the flank of a volcano.
Mudflows are common hazards associated with stratovolcanoes and can happen even without an eruption. They occur whenever floods of water mixed with ash, loose soil, or hydrothermal clay sweep down valleys that drain the sides of large stratovolcanoes. Heavy rainfall or earthquake-induced avalanches of ice or hydrothermal clay also can cause mudflows on steep volcanoes during periods of repose between eruptions. Not all volcanic phenomena are destructive. A lava flow may engulf and bury the land, but new soil and vegetation eventually develop. In warm, humid climates the recovery is rapid; a few decades will suffice to hide the rocky surface of solidified lava flows. In desert or Arctic climates, on the other hand, recovery is slower; flows more than 1,000 years old may still retain their barren appearance. Volcanic ash slowly weathers to form rich, loamy soils. Climate is subject to the effects of volcanic activity. High ash clouds, especially if they are rich in sulfur dioxide, can inject much fine dust and aerosal droplets of sulfuric acid into the stratosphere, above tropospheric rain clouds. Their height greatly increases the residence time of these fine particles in the atmosphere—they are not washed quickly back to Earth but spread slowly into haze layers that can blanket a hemisphere or even the entire Earth. |
Pros and Cons of VolcanoesSome pros of volcanoes are:
*Create new islands and land. *Provide habitat to pioneer speices. *Create economic mineral deposits. *Create beautiful landscapes. *Generate tourism. Some Cons of volcanoes are: *Destroy old habitat and crops. *Destroy cities, towns, and communities. *Displaces population. *Kills people and animals. *Disrupt commerce. *Generate tsunamis. |