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Submarine volcano threatens Hawaii
Truende undervanns vulkan truer Hawaii.
|Tema:||Vulkaner og jordskjelv||Verktøy:|
Southeast of the Hawaiian islands in the Pacific Ocean a new volcano is born in the deep. The scientists fears that an enormous wave will appear close to Hawaii.
All of the sudden south east of Hawaii a new island is born. Until now, no one has seen it because of the volcano Loihi. A volcano that is over 1000 meters high. But the new born island can start an huge wave on over 30 meters. This wave will stream over the islands near by, and kill thousands.
All of the Hawaiian islands are volcanoes. They have appeared because magma(melted mass) from sources about 60 kilometres into the earth streams up through the crust of the earth and shapes volcanoes. Places where this happens are named ‘Hotspots’. Since the Pacific Oceans continental plate, that the islands lays on, through times has moved north east over the hotspot, it is created a group of islands. Repeated volcano breaks through thousands of years has made the volcanoes grow, and one after one the volcanoes has raised to the surface as new islands. At the north east it is laying islands that didn’t make it to the surface.
It the 1970 ties the island was found with echo. But when they found the island it was found 6000kilometer from the eastern Pacific back. So it has wandered to the position it has now, longer north west. But a submarine expedition, that were looking for a serial of small earthquakes in the area show that Loihi was an active volcano and much younger than the 100 million year old sea bottom around it. It was than people started understanding that a new island was under appearance.
To day we know much more about Loihi, “The Long”, and it is detailed pictures of the 4000meter tall volcano. Loihi is about 100 000 years old and will probably come to the surface in about 50 000 years. “A short moment”. Loihi is cheering a hotspot with the active volcanoes Kailauea and Mauna Loa. It is very many smaller earth quakes there and the landscape is often changed by lava streams.
The scientists at Hawaii Undersea research centre got allot to do July 1996 because of many small earthquakes. With in 3 weeks over 5000 smaller earthquakes were registrated, the biggest was 5 on the richters scale. The HURL scientists rushed to the epi-center, the earthquakes centre, to watch the island grow, but found only blurry and hot water. The scientists to many tests and found out that Loihi didn’t grow, but only got 300meter smaller than before the earth quakes. 75 million cubic meters had fell of, and were the top of Loihi was it was now just a big crater. But the Hawaiian people was lucky, if all the 75million cubic meter earth had fell of at once it would have been a disaster. A enormous wave on 30 meters would have streamed over the whole Hawaii.
These waves is also named “tsunami”, witch is a Japanese word and means “harbour wave”, but to day it is am international word for waves that are made with submarine earthquakes.
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