09 December 2007

Indonesia: Center Of The Earth?


I recently thought that perhaps Indonesia is the center of the Earth since three of the most powerful volcanic explosion in mankind history happened in this archipelago. I am not the expert on this matter, that's why i will quote some information from Wikipedia.

Number Three: Krakatoa Explosion

Krakatoa or Krakatau or Krakatao is a volcanic island in the Sunda Strait between Java and Sumatra in Indonesia. The name is used for the island group, the main island (also called Rakata), and the volcano as a whole. It has erupted repeatedly, massively, and with disastrous consequences throughout recorded history. The best known eruption culminated in a series of massive explosions on August 26-27 1883.

The 1883 eruption ejected more than 25 cubic kilometres of rock, ash, and pumice, and generated the loudest sound historically reported: the cataclysmic explosion was distinctly heard as far away as Perth in Australia approx. 1,930 miles (3,110 km), and the island of Rodrigues near Mauritius approx. 3,000 miles (5,000 km). Near Krakatoa, according to official records, 165 villages and towns were destroyed and 132 seriously damaged, at least 36,417 (official toll) people died, and many thousands were injured by the eruption, mostly from the tsunamis which followed the explosion.

The eruption destroyed two thirds of the island of Krakatoa. Eruptions at the volcano since 1927 have built a new island in the same location, called Anak Krakatau (child of Krakatoa)

Number Two: Tambora Explosion

Mount Tambora (or Tomboro) is an active stratovolcano on Sumbawa island, Indonesia. Sumbawa is flanked both to the north and south by oceanic crust, and Tambora was formed by the active subduction zones beneath it. This raised Mount Tambora as high as 4,300 m (14,000 ft), making it one of the tallest peaks in the Indonesian archipelago, and drained off a large magma chamber inside the mountain. It took centuries to refill the magma chamber, its volcanic activity reaching its peak in April 1815.

Tambora erupted in 1815 with a rating of seven on the Volcanic Explosivity Index; the largest eruption since the Lake Taupo eruption in AD 181. The explosion was heard on Sumatra island (more than 2,000 km or 1,200 mi away). Heavy volcanic ash falls were observed as far away as Borneo, Sulawesi, Java and Maluku islands. The death toll was at least 71,000 people, of which 11,000–12,000 were killed directly by the eruption; most authors estimated 92,000 people were killed but this figure is based on an overestimated calculation. The eruption created global climate anomalies; 1816 became known as the Year Without a Summer because of the effect
on North American and European weather. Agricultural crops failed and livestock died in much of the Northern Hemisphere, resulting in the worst famine of the 19th centur

During an excavation in 2004, a team of rchaeologists discovered cultural remains buried by the 1815 eruption. They were kept intact beneath the 3 m (10 ft) deep pyroclastic deposits. Dubbed
the Pompeii of the East, the artifacts were reserved in the positions they had occupied in 1815.

The Year Without Summer

It is now generally thought that the aberrations occurred because of the 5 April Р15 April 1815 volcanic eruptions of Mount Tambora on the island of Sumbawa in the Dutch East Indies (modern-day Indonesia) which ejected immense amounts of volcanic dust into the upper atmosphere. Other volcanoes were active during the same time frame: La Soufri̬re on Saint Vincent in the Caribbean in 1812 Mayon in the Philippines in 1814. These other eruptions had already built up a substantial amount of atmospheric dust. As is common following a massive volcanic eruption, temperatures fell worldwide because less sunlight passed through the atmosphere.

As a consequence of the series of volcanic eruptions, crops in the above cited areas had been poor for several years; the final blow came in 1815 with the eruption of Tambora. In America, many historians cite the "Year Without a Summer" as a primary motivation for the western movement and rapid settlement of what is now western and central New York and the American Midwest. Many New Englanders were wiped out by the year, and tens of thousands struck out for the richer soil and better growing conditions of the Upper Midwest (then the Northwest Territory).

Europe, still recuperating from the Napoleonic Wars, suffered from food shortages. Food riots broke out in Britain and France and grain warehouses were looted. The violence was worst in landlocked Switzerland, where famine caused the government to declare a national emergency. Huge storms, abnormal rainfall with floodings of the major rivers of Europe (including the Rhine) are attributed to the event, as was the frost setting in during August 1816. A BBC documentary using figures compiled in Switzerland estimated that fatality rates in 1816 were twice that of average years, giving an approximate European fatality total of 200,000 deaths.

The eruption of Tambora also caused Hungary to experience brown snow. Italy experienced something similar, with red snow falling throughout the year. The cause of this is believed to have been volcanic ash in the atmosphere.

In China, unusually low temperatures in summer and fall devastated rice production in Yunnan province in the southwest, resulting in widespread famine. Fort Shuangcheng, now in Heilongjiang province, reported fields disrupted by frost and conscripts deserting as a result. Summer snowfall was reported in various locations in Jiangxi and Anhui provinces, both in the south of the country. In Taiwan, which has a tropical climate, snow was reported in Hsinchu and Miaoli, while frost was reported in Changhua

Number One: Toba Explosion?

The Toba eruption (the Toba event) occurred at what is now Lake Toba about 67,500 to 75,500 years ago. It had an estimated Volcanic Explosivity Index of 8 (described as "mega-colossal"), making it possibly the largest explosive volcanic eruption within the last twenty-five million years. Bill Rose and Craig Chesner of Michigan Technological University deduced that the total amount of erupted material was about 2800 cubic km (670 cubic miles) — around 2,000 km³ of ignimbrite that flowed over the ground and around 800 km³ that fell as ash, with the wind blowing most of it to the west. By contrast, the 1980 eruption of Mount St. Helens ejected around 1.2 cubic km of material, whilst the largest volcanic eruption in historic times, at Mount Tambora in 1815, emitted the equivalent of around 100 cubic kilometres of dense rock and created the "Year Without a Summer" as far away as North America.

The Toba eruption was the latest of a series of at least three caldera-forming eruptions which have occurred at the volcano. Earlier calderas were formed around 700,000 and 840,000 years ago. To give an idea of its magnitude, consider that although the eruption took place in Indonesia, it deposited an ash layer approximately 15 cm (6 in) thick over the entire Indian subcontinent; at one site in central India, the Toba ash layer today is up to 6 m (20 feet) thick and parts of Malaysia were covered with 9 m of ashfall. In addition it has been calculated that 1010 metric tons of sulphuric acid was ejected into the atmosphere by the event, causing acid rain fallout.

The subsequent collapse formed a caldera that, after filling with water, created Lake Toba. The island in the center of the lake is formed by a resurgent dome.

Though the year can never be precisely determined, the season can: only the summer monsoon could have deposited Toba ashfall in the South China Sea, implying that the eruption took place sometime during the northern summer. The eruption lasted perhaps two weeks, but the ensuing "volcanic winter" resulted in a decrease in average global temperatures by 3 to 3.5 degrees Celsius for several years. Greenland ice cores record a pulse of starkly reduced levels of organic carbon sequestration. Very few plants or animals in southeast Asia would have survived, and it is possible that the eruption caused a planet-wide die-off. There is some evidence, based on mitochondrial DNA, that the human race may have passed through a genetic bottleneck within this timeframe, reducing genetic diversity below what would be expected from the age of the species. According to the Toba catastrophe theory proposed by Stanley H. Ambrose of the University of Illinois at Urbana-Champaign in 1998, human populations may have been reduced to only a few tens of thousands of individuals by the Toba eruption.

1 comment:

********Icha******** said...

I can't imagine that low temperature could made such a teribble disaster. Thank God, i live in Indonesia, which only has two seasons.

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