Monday, March 21, 2011
MDM SURIADI, Please look to the links for the sections to bemarked.THANK YOU :):):D
VolcanoeGeo
6:41 AM
1.
http://www.scribd.com/doc/323747/1816-Eruption-of-Mt-Tambora-The-year-without-summer
VolcanoeGeo
6:31 AM
The Tambora eruption is estimated to have rated 7 (or super-colossal) on thevolc anic explosivity index (VEI), which runs from 0 to 8. By comparison, the 1981 Mt St. Helens eruption rated 5, and the Krakatoa eruption rated 6. Montgomery (p 110) quotes an estimate that the Krakatoa explosion was the equivalent of 100 million tons of dynamite. The Tambora eruption did not occur as a single event, but rather as a series of events which climaxed between April 10 and April 15. Most accounts give April 12 as the day the mountain blew its top off. The Tombora eruption was comfortably the largest explosion in reliably recorded history. It also threw more debris into the atmosphere than any other eruption in history. Tambora put 25 times more debris into the atmosphere than the 1980 Mount St. Helens eruption, and about 5 times as much as the 1991 Mount Pinatubo eruption. The eruption column reached a height of 28 miles.
EFFECTS ON THE IMMEDIATE AREA
Before Mount Tambora erupted, it is estimated to have been about 4,000m high. The eruption reduced it to 2851m, and left behind a caldera 7 km across. We must rely on contemporary reporting to chronicle most of the effects of the explosion. I have summarized the effects below. The concussions produced by the explosions are said to have been felt for 1,000 miles all around, and the sound was reported to be heard 1,700 miles distant from the volcano. In European settlements 200 and 750 miles away the sounds of the eruption were thought to be cannon fire, and ships and soldiers were despatched to investigate what were assumed o be attacks on nearby outposts. In Java, some 300 miles west the day was darkened by the ash, which fell several inches deep. Closer to ground zero, the rooves of houses 40 miles from the eruption collapsed under the weight of ash. All vegetation on several nearby islands died, significant masses of pumice were reported in the ocean off the western coasts of Sumatra, and the immediate area death toll was around 92,000. 10,000 died from the direct effect of the explosion, lava flows, falling debris and pyroclastic flows, with another 82,000 dying subsequently through starvation and disease. The eruption generated an hour long and extremely destructive "whirlwind", and the sea rose 12 feet above its high tide mark, causing widespread flood damage. It was 5 years before new vegetative growth returned to the area within 250 miles from the eruption.
CLIMATIC EFFECTS OF LARGE VOLCANIC ERUPTIONS
Large, explosive volvanic eruptions can punch huge amounts of gasses and dust high into the atmosphere. The gasses have a long term effect on atmospheric composition (and subsequent climate variations). However, volcanic dust is another story in the short term. Volcanic dust takes months to circulate the globe in the upper atmosphere, and years to settle out. While the dust is in the upper atmosphere it can have a profound effect on the short term global climate. The dust takes some months to circle the globe, and while it is in the upper atmosphere it is postulated that it filters out or blocks a portion of the incoming solar radiation. This in turn lowers the temperatures in the lower atmosphere (including that prevailing at the surface). Meanwhile, a temporary spike in sulfur rich gasses combines with water vapour to form more sulfuric acid droplets in the upper atmosphere. These droplets both absorb solar radiation, and scatter it back to space. Recently, better understanding of these processes, allied to better instrumentation, has meant that some direct correlations have been made between major explosive volcanic events and subsequent short term climatic "blips". To use a recent and well studied example, the 1991 eruption of Mt. Pinatubo is thought to have been responsible for a global temperature lowering of 0.5 deg C the following year. The delay in measureable effect is explained by the time it takes for such gasses and dust to spread around the globe. 0.5 deg C might not seem much, but in marginal agricultural environments it is enough to delay the arrival of spring thaws, enough to project killing frosts into the growing season, and enough to shorten the growing window.
VolcanoeGeo
6:14 AM
In order to reduce the negative effects of a volcanic eruptions, there are many things we can do to play a part. Well, when we do our part to reduce the negative effects, we can save many lives and minimise the destructions caused by the volcanic eruptions.
There are many things that we can do to reduce the negative effects of a volcanic eruption.
You could
use Hazard Mapping and Satellite Monitoring so you can tell exactly when the volcano will erupt. By doing so, you will be like predicting things about the volcano that is going to erupt. You will be able to warn those people living in the area beforehand.
You could also
use barrier walls to penetrate the lava flow and
use diversionary lava channels.
If you are staying in places near an active volcano, you should
practice emergency drills and have a supply of emergency food and water in case the valcano erupts unexpectly.
VolcanoeGeo
4:43 AM
Thursday, March 17, 2011
Why do people continue living near volcanoes?
Before we discuss about that topic, lets take a look at what happened to Mount Tambora in 1816.
In the summer of 1816, the dense volcanic ash from Mount Tambora's eruption blew into the skies over the Northern Hemisphere. The haze of suspended ash filtered the sun from the people and crops below. Unseasonably low temperatures caused frost, crop failure, famine, disease and death across Europe and North America. Historians refer to this isolated event as "The Year Without a Summer
After the volcanic eruption of Mount Tambora, thick layers of ash ruined crops on the islands of Bali, Lombok, Sulawesi and Sumbawa. The resulting famine throughout Indonesia turned so severe, islanders sold themselves as slaves to traders and gave away their children in exchange for rations of rice.
But still, to this day, there are people living near Mount Tambora as if nothing had happened and nothing is going to happend.
WHY?
If we are to ask ourselves this question, many of us will be able to come up with one very common answer. The answer is,
the land is fertile. Which means, the soil is great for farming. When lava starts to overflow, the lava becomes a source of nutrients for the plants to grow.
The minerals inside the lava acts as a form of fertilizer for plants.
Another reason is that the
land is cheaper, the
soil is rich and grows ,example, wine very well.
In some cases,
poverty is the reason why people continue to live near volcanoes, they have always lived there and do not have enough money to move.
However there are many other reasons why people have and continue to settle near to volcanoes.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.
Here are a few photos of the eruption of mount tembora and people living around volcanic areas.
VolcanoeGeo
3:33 AM
Wednesday, March 16, 2011
There are many ways to predict when the volcanos is going to erupt. Well, when we predict, we want to know when the volcano is going to erupt, how destructive will that eruption be and many other measures. But before we predict, we need to know why is it that we want to know all those stuff that is going to happen in future. Well, the answer is sinple. so that people can be well prepared. And so that we can minimise the destructions that the lava and that ashes are going to cause.
In predicting an eruption of a volcano, we can use the
seismometer.
A seismometer (or seismograph) is a sensor that detects the intensity of earthquakes caused by magma that is moving. well, the seismometer does not actually 'predict' when the volcano is going to occur but it detect the intensity of earthquakes caused by the magma so we can roughly predict by ourselves when and how the eruption is going to be.
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. when the scientists finds out that the level of magma is moving upwards, it means, there is going to be an eruption very soon so it can warn people around it.
Scientists also take temperatures and gauge gas by using a
Landsat satellite. The satellite uses infared sensors to detect temperatures and changes in volcanoes. Aircraft monitors the amount of gas released from the ground. An increase in sulfur dioxide and other gases usually means that there could be volcanic eruptions.
Volcanologists use these instruments to successfully predict eruptions which saves many lives. Scientists are trying to develop new ways to predict future eruptions.
For normal people living around the volcano areas, there are many simply ways of predicting the volcanic eruption without using any scientific equipments.
One example is to look for plumes of smoke or clouds of gas on or around the volcano that aren't typically there. As magma flows into the chambers beneath a volcano and rises to the surface, it can cause different gases to be released, which geologists keep a close eye on for changes in quantity or composition.
Look out for any changes in seismic activity near the volcano. Many volcanoes continuously give off rumbles or tremors, but a sudden increase in the number or strength of these quakes can indicate impending eruption
VolcanoeGeo
2:17 AM
When a volcano erupts, it make make many changes to its surroundings, the environment and the life of people living around it both,
positive and negative. Here are some examples of negatives affects that follows the eruptions of mountains such as
mount Tambora.
THE ENVIRONMENT
The immediate effects include the stench of sulfuric gas in the air, and the raised sea temperatures caused by the pyroclastic flow entering the water. Both of these effects will only last a very short while.
THE PEOPLE
Lots of people would also be left homeless. There would be a massive decline of the country's population due to whooping numbers of casualties from the hot lava and or the suffocating volcanic ash emmited, which is cause by inadequate information on the eruptions 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.
There will also be a huge problem concerning 'Lahar', every time it rains. When the pyroclastic materials mix with large amounts of water, 'lahars' (which is a type of mudflow) are formed, which can flood and bury not only houses but also towns. The ash and lava that rains over the land and buries it is also a problem. 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. There might also be silting in the rivers and lakes, which stops boats from navigating through, as the depth becomes much shallower. Of course there are also some positive affects that a volcanic eruption can cause. For example, the beautiful island of Hawaii was formed because of a volcanic eruption. Not only that, after a volcanic eruption, because of the lava and ashes, the soil near the volcano will be very fertile.
VolcanoeGeo
12:36 AM
