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Is Nyiragongo atop a growing mantle plume? 13 March 2009

Posted by admin in Africa, Congo (Dem. Rep.), current research, geoscience, Nyiragongo, volcanology.
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The highly fluid, fast-moving lava produced by Nyiragongo volcano in the Democratic Republic of the Congo presents a dangerous volcanic hazard. In January 2002 the volcano erupted 14–34 × 106 m3 of lava from vents on its southern flanks, engulfing thousands of buildings in the nearby city of Goma and surrounding villages, killing about 50 people and leaving 120,000 people homeless. Twenty-five years earlier, in January 1977, a large death toll – possibly in the hundreds, and thought by some to be in the thousands – resulted from a similar eruption which produced lava flows with peak speeds estimated at 100km/h.

So what makes Nyiragongo’s lava unique? New research by Asish Basu of the University of Rochester (and others), published in Chemical Geology, suggests that a mantle plume is emerging beneath the volcano, feeding it with magma from a very deep source:

‘This is the most fluid lava anyone has seen in the world … It’s unlike anything coming out of any other volcano. We believe we’re seeing the beginning of a plume that is pushing up the entire area and contributing to volcanism and earthquakes.’

Basu analyzed the lava, which resides in the world’s largest lava lake—more than 600 feet wide inside the summit of Nyiragongo—and found that the isotopic compositions of neodymium and strontium are identical to ancient asteroids. This suggests, says Basu, that the lava is coming from a place deep inside the Earth where the source of molten rock is in its pristine condition.

For more details, see the press release from the University of Rochester. The paper itself is available to subscribers or to purchase via ScienceDirect:

  • Ramananda Chakrabarti, Asish R. Basu, Alba P. Santo, Dario Tedesco & Orlando Vaselli, ‘Isotopic and geochemical evidence for a heterogeneous mantle plume origin of the Virunga volcanics, Western rift, East African Rift system’, Chemical Geology, vol. 259, issues 3-4 (25 February 2009, pp. 273-289 [doi:10.1016/j.chemgeo.2008.11.010]

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Samoa created by a ‘hotspot’, new study concludes 18 June 2008

Posted by admin in current research, geoscience, volcanology.
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A new study published in the June issue of Geology concludes that Samoa was formed by a ‘hotspot’ fed by a mantle plume beneath the Pacific Ocean, reports ScienceDaily: ‘Samoa Found To Be In Path Of Geological Hotspots, Adding Fuel To Debate Over Origins Of Volcanic Chains’.

The Volcanism Blog