Among the few lava lakes present on the planet, Nyiragongo ( DRC), Erta Ale (Ethiopia) , Kilauea (Hawaii) and Erebus (Antarctica) , the latter holds a special place .
Its phonolitic magma is 100 times more viscous than basaltic magma of Kilauea or Erta Ale
This lava lake , active since the 70s, was analyzed by volcanologists for over 40 years. During the first decades , scientists had only a few weeks in summer to gather measurements and valuable comments . The installation of permanent equipment have allowed monitoring throughout the year .
Erebus - photo MEVO 11.2012
The breath of the sleeping dragon :
This ongoing monitoring revealed the regularity of the " breath of Erebus ."
There a few years ago , Oppenheimer, a volcanologist at the University of Cambridge , has measured the plume of gas still present volcano : the total amount of gas , composed almost equally of carbon dioxide and water with added a little sulfur dioxide and HCl , follows a cycle of 10 minutes , with both quantitative and qualitative changes .
The analysis of several hundreds of thousands of images allowed to deduce the motion vectors surface , and the average surface speed of the lava lake . Since 2004, and although the apparent surface of the lava lake has decreased by a factor 4, the pulsatile behavior remained constant , showing cycles of surface speed between 5 and 18 minutes. The average surface speed is from 3 to 20 cm / sec .
In addition, it is noticed that the surface of the lake rises and down 2 to 3 meters , in conjunction with the cycle gas ten minutes.
Erebus - continuous degassing - photo Nat Geo / Carsten Peter
Erebus - 01.12.2012 - the lava lake - photo MEVO
Eructations and plumbing system of the volcano :
Differentiation between this " breathing " and " burping " of the volcano during eruptions allows a better understanding of the plumbing system of Erebus .
During eruptions , large gas bubbles emerge and burst into the lava lake , making splash on the slopes ... some lava bombs up to the size of a bus. These two behaviors are not coupled , and scientists believe that the gas bubbles causing the projection of bombs rise from a greater depth . They have indeed noted that the cycles of gas continue even when eruptions do sharply lower the level of the lava lake .
Erebus - Clive Oppenheimer near a large anorthoclase phonolite bomb - December 2013 - photo MEVO
Erebus plumbing system - doc. MEVO
Sources :
- Live Science - Antarctic lava lake huffs and puffs like a sleeping dragon - link
- ScienceDirect / Earth and Planetary Science Letters - Decadal persistence of cycles in lava lake motion at Erebus volcano, Antarctica by Nial Peters ,CliveOppenheimer, Philip Kyle, Nick Kingsbury / 03.2014
- MEVO - Mount Erebus Volcano Observatory - link
- Mantle to surface degassing of alkalic magmas at Erebus volcano, Antarctica - By Clive Oppenheimer & al. - link
