Super Volcanoes = human extinction?

LuCkY-sTaR

Pada 13 & 14 Mac lalu, BBC telah menyiarkan satu dokumentari/drama fiksyen berkenaan Super Volcano yg akan meletus di Yellowstone Park, Wyoming, US. Dikatakan :-

- Geologists say there is a real risk that sooner or later a supervolcano will erupt with devastating force, sending temperatures plunging on a hemispheric or even global scale.

- A report by the BBC Two programme Horizon on one supervolcano, at Yellowstone national park in the US, says it is overdue for an eruption. Yellowstone has gone off roughly once every 600,000 years. Its last eruption was 640,000 years ago.

- Colossal impact on a global scale.

- A super-eruption is also five to 10 times more likely to happen than an asteroid impact, the report claims.

- The fallout from a super-eruption could cause a "volcanic winter", devastating global agriculture and causing mass starvation. (The eruption throws cubic kilometres of rock, ash, dust, sulphur dioxide and so on into the upper atmosphere, where they reflect incoming solar radiation, forcing down temperatures on the Earth's surface. It's just like a nuclear winter).

- The volcanic winter resulting from a super-eruption could last several years or decades, depending on the scale of an eruption, and according to recent computer models, could cause cooling on a global scale of 5-10C

- The crater from the last super-eruption, 640,000 years ago, is large enough to fit Tokyo - the world's biggest city - inside it.

- The report, released by The Geological Society in the UK, identifies at least 31 sites where super-eruptions have occurred in the past. They include Lake Taupo in New Zealand and the Phlegrean Fields near Naples, Italy.

ibnur

Ni cerita pasal ni, tsunami pun ada.

http://www.drgeorgepc.com/Vocano1883Krakatoa.html


Over a century ago, on August 26,1883, the island volcano of Krakatau ("Krakatoa") in Indonesia, a virtually unknown volcanic island with a history of violent volcanic activity, exploded with devastating fury. The eruption was one of the most catastrophic natural disasters in recorded history. The effects were experienced on a global scale. Fine ashes from the eruption were carried by upper level winds as far away as New York City. The explosion was heard more than 3000 miles away. Volcanic dust blew into the upper atmosphere affecting incoming solar radiation and the earth's weather for several years.
A series of large tsunami waves generated by the main explosion, some reaching a height of nearly 40 meters (more than 120 feet) above sea level, killed more than 36,000 people in the coastal towns and villages along the Sunda Strait on Java and Sumatra islands. Tsunami waves were recorded or observed throughout the Indian Ocean, the Pacific Ocean, the American West Coast, South America, and even as far away as the English Channel

ibnur

Upper Atmosphere Effects

Ash from the eruptions was propelled to a height of 50 miles (80 kilometers) in the upper atmosphere blocking the sun and plunging the surrounding region into darkness for two and a half days.
Dust and ash from the eruption encircled the Earth in 13 days forming a cloud which, by September 9, 1883, had covered completely the upper atmosphere along a belt in the equatorial zone. Three months after the eruption this belt of volcanic dust of fine particles of dust had spread to higher latitudes causing unusually spectacular red sunsets and other interesting atmospheric effects. Blue and green suns were also observed. Breathtaking sunsets were observed during the winter months of 1884 in both American and Europe. Unusual sunsets continued for almost 3 years.


Climatic Changes

It has been estimated that at least 21 cubic Km (appr. 11 cubic mile) was ejected from the eruption of Krakatoa and that at least 1 cubic mile of the finer material was blown to a height of about 17 miles (27 Km). The volcanic dust blown into the upper atmosphere was carried several times around the earth by air currents. This volcanic dust veil not only created the spectacular atmospheric effects described previously but acted also as a solar radiation filter, reducing the amount of sunlight reaching the surface of the earth. In the year following the eruption, global temperatures were lowered by as much as 1.2 degree Centigrade on the average. Weather patterns continued to be chaotic for years and there were major climatological changes which affected the entire globe. Temperatures did not return to normal until five years later, in 1888.