Scientists discover long 'fingers' of heat beneath Earth - Indian Express

PTI : Washington, Fri Sep 06 2013, 14:38 hrs Discovery helps explain the "hotspot volcanoes" that give birth to islands such as Hawaii, Tahiti. (Thinkstock) Scientists seeking to understand the forces at work beneath the Earth's surface have detected previously unknown "fingers" of heat, some of them thousands of miles long, in our planet's upper mantle. The discovery helps explain the "hotspot volcanoes" that give birth to island chains such as Hawaii and Tahiti. Many volcanoes arise at collision zones between the tectonic plates, but hotspot volcanoes form in the middle of the plates, researchers said. Geologists have hypothesised that upwellings of hot, buoyant rock rise as plumes from deep within Earth's mantle - the layer between the crust and the core that makes up most of Earth's volume - and supply the heat that feeds these mid-plate volcanoes. Computer modelling approach, developed by University of Maryland seismologist Vedran Lekic and colleagues at the University of California Berkeley, has produced new seismic wave imagery which reveals that the rising plumes are, in fact, influenced by a pattern of finger-like structures carrying heat deep beneath Earth's oceanic plates. Seismic waves are waves of energy produced by earthquakes, explosions and volcanic eruptions, which can travel long distances below Earth's surface. As they travel through layers of different density and elasticity, their shape changes. A research team led by Scott French found finger-like channels of low-speed seismic waves flowing about 193 to 354 kilometres below the sea floor, and stretching out in bands about 1127km wide and 2253km apart. The researchers also discovered a subtle but important difference in speed: at this depth, seismic waves typically travel about 4 to 4.8 kilometres per second, but the average seismic velocity in the channels was 4 per cent slower. Because higher temperatures slow down seismic waves, the researchers infer that the channels are hotter than the surrounding material. "We estimate that the slowdown we're seeing could represent a temperature increase of up to 200 degrees Celsius," said French, the study's lead author. ... contd. ALSO READ PayPal app adds more mobile wallet features Google argues for right to continue scanning Gmail Samsung to launch 2 ultra high definition TVs in India this month NASA evaluates four sites for 2016 Mars mission Please read our terms of use before posting comments TERMS OF USE: The views, opinions and comments posted are your, and are not endorsed by this website. You shall be solely responsible for the comment posted here. The website reserves the right to delete, reject, or otherwise remove any views, opinions and comments posted or part thereof. You shall ensure that the comment is not inflammatory, abusive, derogatory, defamatory &/or obscene, or contain pornographic matter and/or does not constitute hate mail, or violate privacy of any person (s) or breach confidentiality or otherwise is illegal, immoral or contrary to public policy. Nor should it contain anything infringing copyright &/or intellectual property rights of any person(s). via Science - Google News http://news.google.com/news/url?sa=t&fd=R&usg=AFQjCNFFnnWM8ZsIsISFIebacDQsc4AHvg&url=http://www.indianexpress.com/news/scientists-discover-long-fingers-of-heat-beneath-earth/1165527/

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