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Victoria University Antarctic Research Expedition Science and Logistics Reports 1974-75: VUWAE 19

Erebus expedition (McMurdo Volcanics project)

Erebus expedition (McMurdo Volcanics project)

  1. The geology at the northern end of Black Island was examined and no large differences from early reports were found. A drill site for the Dry Valley Drilling Project was located and recommended to officials of the project. No hole was drilled however.
  2. The activity pattern of Mt. Erebus was observed and can be compared to observations made in November 1973 by Kyle and in 1972/73 by Keys, Kyle and others.

    Mt. Erebus contains a permanent convecting lava lake of anorthoclase phonolite (kenyte) composition. The lake has expanded in size since 1973. Only 3 permanent lava lakes exist in the world. The others are in Ethiopia and Zaire (and because of political situations in those countries are inaccessible to volcanologists). Erebus is unique in being the only phonolite lava lake, the others are basaltic.

    Although the lava lake could not be sampled because of dangerous eruptions in the inner crater, bombs were frequently thrown out on to the main crater floor and crater rim and could be sampled. The only difference between such material and lava collected from the lava lake is probably the loss of volatile gases such as F, S, and Cl from the bombs.

    Lambert (N.Z. Press Association) and Kyle witnessed an eruption from the inner crater rim. This was the smaller of 2 eruptions recorded on the Scott Base seismograph net. A vent on the south-eastern quadrant (named the active vent) of the inner crater filled rapidly (less than 10 to 15 seconds) with lava. As the lava was about to flow over the rim of the 15 to 20 metre wide vent it exploded violently, - "like a battery of 25 pounders" to quote Lambert. Lambert and Kyle were 150 m away directly in line with the vent, and were thrown to the ground. As they ran for shelter several large bombs were seen flying through the air at close quarters. Keys also witnessed two large eruptions both of which originated in the active vent, and threw molten material more than 300 m above the inner crater floor.

  3. The geology around the flanks of the active cone of Mt. Erebus was examined.