What More Can Be Done To Reduce The Negative Effects Of Volcanic Erruptions?

•    Make tall buildings cone-shaped with a broad base to prevent it from falling over easily from earthquakes that may occur before, after, or during a volcano erruption.
•    Movement of magma, changes in the quantity and quality of gases emitted by the volcanoes, and small earthquakes can serve as signals of volcanic eruptions, so proper monitoring of these signals, ready disaster management techniques and creating awareness among the general public about the hazards of volcanic eruptions, can play an important role in minimizing the losses and saving human lives.
•    Canals could be dug to redirect the lava flow into rivers or seas to reduce the damage it would have done.
•    The people who wish to live in the area should wear masks for awhile so that they don't breathe in the coal dust which may still be floating about the area.
•    Everyone who lives near volcanoes should make sure they are well aqquainted with the area and know immedietly where they should evacuate to if the volcano happens to errupt.

Sources:
http://www.buzzle.com/articles/effects-of-volcanoes.html
http://wiki.answers.com/Q/Explain_the_precautions_that_may_be_taken_to_reduce_the_negative_effects_of_earthquakes_and_volcanoes

Why Do People Continue To Live Near Volcanoes?

   When a volcano erupts, it throws out a lot of ash. At short notice, this ash can be very harmful to the environment, but on the long term, the ash layer, which contains many useful minerals, will be converted to a very fertile soil. Nearly everywhere volcanoes are located people use the rich soil for farming.  Even after an eruption, people still return because of the fertile soil.
   Also, volcanoes can produce very spectacular scenery like the beautiful sunsets caused by explosive eruptions.  Other features include plant-rich environments, stunning eruptions, beautiful lava fountains etc.
   Small active volcanoes at Papua-New-Guinea, deep beneath the sea, have thrown precious metals out of the earth.  The sea-bottom there contains so much gold and other metals that commercial ventures are being investigated. There, cold sea-water trickles through the rocky bottom downwards where it is being heated by magma chambers.  Then, very hot water (up to 350 degrees Celsius) rises.  The hot water takes several minerals with it on the way upwards.  When these minerals come in touch with the cold sea-water they will precipitate on the sides of the little volcano.
   Magna rising from deep inside the earth contains a range of minerals. As the rock cools, minerals are precipitated out and, due to processes like the movement of superheated water and gasses through the rock, different minerals are precipitated at different locations. This means that minerals such as tin, silver, gold, copper and even diamonds can be found in volcanic rocks. Most of the metallic minerals mined around the world, particularly copper, gold, silver, lead and zinc are associated with rocks found deep below extinct volcanoes. This makes the areas ideal for both large scale commercial mining and smaller scale local activities by individuals and small groups of locals. Active and dormant volcanoes have the same mineralisation, so like extinct volcanoes, they are rich sources of minerals. Hot gasses escaping through vents also bring minerals to the surface, notably sulphur, which collects around the vents as it condenses and solidifies. Locals collect the sulphur and sell it.
   Geothermal energy means heat energy from the earth. It's unusual to use the heat directly, by building your house on top of a steam vent for example, because it's unpredictable, dangerous and messy.
The heat from underground steam is used to drive turbines and produce electricity, or to heat water supplies that are then used to provide household heating and hot water. Where steam doesn't naturally occur it is possible to drill several deep holes into very hot rocks, pump cool water down one hole and extract steam from another hole close by. The steam isn't used directly because it contains too many dissolved minerals that could precipitate out and clog pipes, corrode metal components and possibly poison the water supply.
Countries such as Iceland make extensive use of geothermal power, with approximately two thirds of Iceland's electricity coming from steam powered turbines. New Zealand and to a lesser extent, Japan, also make effective use of geothermal energy.
   Volcanoes attract millions of visitors every year, for different reasons. As an example of the wilder side of nature, there are few things that can beat seeing an erupting volcano blowing red hot ash and rock thousands of feet into the air. Even the less active ones that are just puffing out steam and smoke are impressive sights and attract tourists from around the world. Around the volcano may be warm bathing lakes, hot springs, bubbling mud pools and steam vents. Tourism creates jobs in shops, restaurants,hotels and tourist centres / national parks. Locals economies can profit from volcanism throughout the year, whereas skiing, for example, has only a limited winter season.
   A lot of volcanic products can be used in everyday life. Sulphur, for example, can be used as an ingredient in matches, or in medicine, while the finer volcanic deposits, such as the gravels and sands found in rivers, can be used as building materials.
   Due to the infrequency of some volcanic eruptions, some people, particularly those who have not experienced a volcanic eruption in their lifetime are reluctant to leave their homes in order to move to safety and ignore warning, preferring to live with the threat of a volcanic eruption. Some believe that there will be time to move / be resuced should an eruption begin.
   It should also be recognised that some people have no choice but to live in these areas. In areas of poverty, people do not have the resources available to move and for many farming on the fertile soils in the shadow of a volcano may be the only livelihood they know.


Sources:
http://geobytesgcse.blogspot.com/2007/01/living-with-volcanoes.html
http://www.rps.psu.edu/jan2000/volcano.html
http://www.geography-site.co.uk/pages/physical/earth/volcanoes/why%20people%20live%20near%20volcanoes.html
http://library.thinkquest.org/17457/volcanoes/advantages.php

To What Extent Can Volcanoes Be Successfully Predicted?

•   Seismic activity (small earthquakes and tremors) always occurs when a volcano awakens and prepares to erupt. Some volcanoes normally have continuing low-level seismic activity, but an increase can signify an eruption. The types of earthquakes that occur and where they start and end are also key signs. The seismograph uses a pendulum to record movement of the ground below it. The squiggly lines recorded on paper by a seismograph are called a seismogram.
•   Since magma gives off electric currents, electric meters are used to spot rising magma levels by measuring its electric current. Gravimeters can also detect flowing magma.
•   Scientists also take temperatures by using a Landsat satellite. The satellite uses infared sensors to detect temperature changes in a volcano.
•   As magma nears the surface and its pressure decreases, gases escape. Sulfur dioxide is one of the main volcanic gases, and increasing amounts of it usually mean the arrival of more magma near the surface. Aircrafts monitor the amount of gas released from the ground. An increase in sulfur dioxide and other gases usually means that there could be volcanic eruptions.
•   As magma moves up into a volcano the volcano swells, and distances between points on the volcano (think of dots on a balloon) as well as the elevation at specific points increases. Such a change is a common occurrence prior to an eruption. The tiltmeter is a sensor that uses a laser beam to find the rising or lowering of magma levels by measuring changes in ground elevation.
•   Before an eruption, magma moves into the area beneath the volcano and collects in a magma chamber. Magma gathering in a chamber causes slight swelling of the volcano's slopes. Swelling of the volcano signals that magma has accumulated near the surface. Scientists monitoring an active volcano will often measure track changes in the rate of swelling. Radar satellites that continually orbit the earth can detect as little as a one-millimetre increase in swelling on the flanks of a volcano. An increased rate of swelling--especially if accompanied by an increase in sulfur dioxide emissions and harmonic tremors--is almost a sure sign of an impending erruption.
•   Hydraulic measurements are increasingly used to monitor changes in a volcanoes. Increased gas pressure will make water levels rise and suddenly drop right before an eruption.
•   Volcanic deposit that may be placed on a river bank can easily be eroded which will dramatically widen or deepen the river channel. Therefore, monitoring of the river channels width and depth can be used to assess the likelihood of a future volcanic eruption.
•   Pre-eruption sediment may be picked up by a river channel surrounding the volcano that shows that the actual eruption may be imminent. Most sediments are transported from volcanically disturbed watersheds during periods of heavy rainfall.

Sources:
http://en.wikipedia.org/wiki/Prediction_of_volcanic_activity
http://www.yourdiscovery.com/science/eruption/predicting/index.shtml
http://www.learner.org/interactives/volcanoes/morfore.html
http://library.thinkquest.org/J003007/Disasters2/volcano/predicting/predict.htm

Long-term Impacts Of Volcanoes

Disadvantages

THE PEOPLE
   There will be a massive decline of the country's population due to a large number of casualties. There will also be effects on the economy, depending on the area effected. If it is the financial district, than the wealth of the country will decrease.
   Also, when people revisit the spot where the volcano erupted, they may breathe in the coal dust still floating around the area. Coal dust in the lungs that mining authorities shrugged shoulders about, has been found to be able to kill.
   The area affected by the volcanoes will be barren for quite some time, which will affect the country's food supply, maybe even causing famines.

THE ENVIRONMENT 
   Ash and lava is very difficult to farm on, and it only becomes fertile after a long time, therefore, plant life would be limited, which would also affect the food chain. It may even cause animals to attack humans due to lack of food available or migrate, which will leave the area with little animals for awhile.
   There might also be silting in the rivers and lakes, which stops boats from navigating through, as the depth of water becomes much shallower.

   Eruptions can inject massive quantities of ash into the atmosphere, greatly reducing the solar heating of the Earth and potentially interrupting the global food supply for several years.

   Sulfur from volcanoes has the potential to cool the Earth. Sulfur reacts with water in the air to form sulfuric acid droplets that reflect sunlight hitting Earth, thus blocking some rays. The reduction in sunlight can reduce temperatures for a year or so, until the droplets fall out of the atmosphere.
   When pastures are subjected to ash falls and remobilization of ash by wind, evacuation of livestock to areas with good quality feed and water may be prudent. Even after evacuation, long-term inhalation of ash and exposure to fluorine may result in reduced productivity.

Advantages

THE PEOPLE

   Many people may want to see the spot where the volcano erupted, thus, the volcanoes may become a tourist attraction, thus improving the country's economy.
   The area around the volcano erruption would become fertile, thus increasing the quality of the goods harvested. This, in turn, will lead to an increase in the economy of the country.
   Also,   Volcanoes provide resources for energy extraction, also called geothermal resources.  Heat from the earth's crust is being converted to energy. The big advantages to this type of energy are that it is very clean and the resources are nearly inexhaustible.

THE ENVIRONMENT

   Not all volcanic phenomena are destructive. A lava flow may engulf and bury the land, but new soil and vegetation will 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.

Case Study

Lake Toba is the site of a supervolcanic eruption that occurred 69,000-77,000 years ago, a massive climate-changing event. It is believed to be the largest explosive eruption anywhere on Earth in the last 25 million years. According to the Toba catastropher theory, to which some anthropologists and archeologists subscribe, it had global consequences, killing most humans then alive and creating a population bottleneck in Central Eastern Africa and India that affected the genetic inheritance of all humans today. This theory however, has been largely debated as there is no evidence for any other animal decline or extinction, even in environmentally sensitive species. However, it has been accepted that the eruption of Toba led to a volcanic with a worldwide decline in temperatures between 3-5 degrees C, and up to 15 degrees C in higher latitudes.

SOURCES:
http://library.thinkquest.org/17457/volcanoes/advantages.php
http://en.wikipedia.org/wiki/Lake_Toba

http://volcanoes.usgs.gov/ash/agric/index.html

http://www.digitaljournal.com/article/290899

http://www.msnbc.msn.com/id/36556083/ns/us_news-environment/
http://solidearth.jpl.nasa.gov/PAGES/volc03.html

http://www.britannica.com/EBchecked/topic/632130/volcano/253598/Long-term-environmental-effects
http://wiki.answers.com/Q/What_are_the_short_term_and_long_term_effects_of_volcanoes_on_land#ixzz1GMowRjIA