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Flood Basalt Eruption

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776px-Bathymetry image of the Hawaiian archipelago
A flood basalt or trap basalt is the result of a giant volcanic eruption or series of eruptions that coats large stretches of land or the ocean floor with basalt lava. These eruptions do not produce very much ash. However, they do produce prodigious amounts of greenhouse gases - in particular carbon dioxide. Flood basalts have occurred on continental scales (large igneous provinces) in prehistory, creating great plateaus and mountain ranges. Flood basalts have erupted at random intervals throughout geological history and are clear evidence that the Earth undergoes periods of enhanced activity rather than being in a uniform steady state.


One explanation for flood basalts is that they are caused by the combination of continental drifting and its associated decompression melting, in conjunction with a mantle plume also undergoing decompression melting, producing vast quantities of a tholeiitic basaltic magma. These have a very low viscosity, which is why they 'flood' rather than form taller volcanoes.


The Deccan Traps of central India, the Siberian Traps and the Columbia River Plateau of western North America are three regions covered by prehistoric flood basalts. The two largest flood basalt events in historic time have been at Eldgjá and Lakagigar, both in Iceland. The maria on the Moon are additional, even more extensive, flood basalts. Flood basalts on the ocean floor produce oceanic plateaus.


Flood basalts originate at between 100 and 400 km depth, in the asthenosphere. To obtain a partial fusion as large as that of the traps, expelling huge quantities of lava, it is necessary to have a large heat input. Such fusion can take place near a hotspot, resulting in a mixture of magma from the depths of the hotspot with superficial magma produced by a mantle plume.


On the 22nd January 2002 in Hawaii there is a swarm of earthquakes between the Big Island and the Loihi sea mount. Due to the increased activity the Hawaiian volcano observatory sends a submersible to investigate. The scientists discover there has been a large eruption of lava from the Loihi sea mount adding nearly 900 metres to its height. Over the next six months measurements are taken from boats and it showed that the sea mount was gaining nearly a two metres a week in height due to ongoing eruptions. In October 2002 the Loihi Sea mount breaks the surface for the first time. From November 2002 the eruptions at Loihi become nearly continuous, Mauna Kea, Mauna Loa and Kilauea also begin to erupt in December 2002. In March 2003 Hualalai on the big island and Haleakala on Maui begin to erupt as well. As the eruptions increase in frequency, the Hawaiian Authorities order the evacuation of the Big island and Maui. In 2005 the evacuation of the entire eastern end of the Hawaiian archipelago from Oahu eastward is ordered. By 2006 Maui, Lanai, Molokai and Kahoolawe have joined together into one island and by 2007 it has joined together with the Big Island of Hawaii to form the new island of Maui Nui.


MAUI NUI

New island of Maui Nui

In 2007 cracks start to form along the eastern flanks of Maui Nui, on 27th May 2007 a large section 5 km long and 3 km wide of Maui Nui collapses into the ocean causing a massive tsunami which moves across the Pacific ocean. It hits the west coast of the Americas five hours later. The wave in California is over 50 metres high and destroys massive parts of Los Angeles and San Diego. In San Francisco the waves wash inland and destroy the majority of Sacramento. North and south of California the waves are smaller but still devastating. Seattle, Vancouver (Canada) and Tijuana are hit by waves over 15 metres high. Due to the distance of travel and time it takes to reach the coast the tsunami kills 15,000 - not the several hundred thousand it could have.

The wave hit the entire west coast of the Americas from Alaska to southern Chile, it also hits north island of New Zealand.


From 2005 the eruption causes major global problems due to dramatically enhanced global warming caused by the massive amounts of carbon dioxide being released into the atmosphere. The temperatures started to rise almost immediately.

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