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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]

The Volcanism Blog

Comments

1. DS - 13 March 2009

is this Siberia or India all over again.

2. Thomas Donlon - 14 March 2009

The Indian lava flats formed about the time of the extinction of the dinosaurs – 65 million years ago. The asteroid impact in the Mexican Chicxualub region created shock or seismic waves that led to the Indian lava flats on the opposite side of the earth.

I think the Siberian lava flats also came about from an asteroid impact.

Just a few thousand years ago there were parts of the US that had lava fields – so I guess we could see more moderately sized lava fields.

I wonder if the plume in Africa will start eating away at the crust much like has happened under Yellowstone. I am guessing not – but I also think based on this report that this area must remain very volcanically active for many, many years to come.

3. Michael - 22 March 2009

The Indian Deccan Lavas are not impact generated, the Iridium anomaly of the Impact lies between the Lava flows, so it can’t the cause of the volcanism. In fact, the Deccan Traps began 1million years before the impact!

The Siberian lavas came probably from delamination of very thick and old Lithosphere, as it was replaced with hot Asthenosphere strong volcanism happend there.

The Yellowstone Plume isn’t that strong as you think, it erupts 1000km³ every some 700.000 years… that’s 0.0014km³ per year, much less than the activity of the Nyiragongo Plume which is feeding many Volcanoes!


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