Mount Erebus, Gas and Dust

The continuing activity of Mt. Erebus releases substantial amounts of volcanic particulates and gases into the atmosphere. In addition, a variety of salts are forming on rock surfaces and in the regolith in the area of the summit. The discharge of water vapor by fuma-roles on the summit plateau has caused the growth of spectacular ice towers and warm ground that occurs south of the Main Crater and elsewhere within a radius of less than 1,000 m of its rim. 

The gases vented by the summit of Mt. Erebus consists primarily of water vapor, sulfur dioxide, carbon dioxide, as well as chlorine and fluorine (Rose et al. 1985). These gases and the associated particles are the principal volcanic contaminants of the atmosphere over Antarctica and therefore have been studied by sampling from aircraft and by remote sensing using satellites(e.g., Rothery and Oppenheimer 1994). 

The fumaroles on the summit plateau of Mt. Erebus discharge steam into the atmosphere which condenses rapidly in the cold air and the water then freezes to form hollow ice towers pictured in Eig. 16.21 (Holdsworth and Ugolini 1965). In addition ice caves have formed on the summit plateau where steam is discharged by subglacial vents. Some of these ice caves and the warm ground along the rim of the Main Crater have been used for reereational purposes. 

Salts consisting of halite (Na Cl), thenardite (Na SO ), and sylvite (KCl) identified by Keys (1980) in the Main Crater were also observed in the plume by Chuan et al. (1986). Sulfuric acid droplets and coatings of aerosol particles were found only on December 9,1983, because they are discharged only during small gas eruptions of the lava lake. During these events, the plume also contains particles of native sulfur in crystalline and amorphous form in addition to sulfur dioxide (SO ) and, possibly, hydrogen sulfide (H S). Mid-sized particles of iron oxide occurred in the plume of December 19 but not on December 9. In addition. 

Given the variation in the speed and direction of the wind on Ross Island, the particles in the Erebus plume are dispersed widely such that their surface concentration is below detection. Deposits of volcanic ash that do occur in the East Antarctic ice sheet as well as locally on the surface of valley glaciers and ice caps formed during volcanic eruptions not only of Mt. Erebus but also of the other volcanoes and vents in the Transantarctic Mountains of Victoria Land and in Marie Byrd Land of West Antarctica (Keys et al. 1977 Palais et al. 1982,1983a, b Palais and Legrand 1985 Palais et al. 1989 Radke 1982 Kyle et al. 1982b). 

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