The late 1984 eruption partially filled the inner crater with ejecta that obscured the magma column. The overall impression of the activity was that the magma column height and position had not changed significantly for the past 14 years. The active vent, a small explosion crater adjacent to the lava lake, had re-formed and a small crater was seen around the site of a fumarole that had been active prior to September 1984. The elevation of the new lake was not measured, but it appeared similar to the 1983 lake. A small lava lake, ~15 m in diameter, was in a site similar to that of the former lake. "By December 1985, the inner crater showed some resemblance to its morphology and form prior to September 1984 (figure 7, bottom). However, observations in December 1985 suggest that the inner crater was partially filled with ejecta from the eruptions. An initial interpretation was that the lava lake had frozen over and was domed up. "Inspection of the volcano in October, November, and December 1984 showed that the lava lake was gone (figure 7, middle). Erebus in January 1984 (top), November 1984 (middle), and December 1985 (bottom). Sketch map showing the inner crater at Mt. The eruptions were witnessed from 60 km distance and the explosions could be heard from 2 km.įigure 7. During the increased activity, bombs averaging 2 m long and reaching more than 10 m in length were dispersed radially around the crater rim, to 1.2 km (horizontally) from the center of eruption in the inner crater. Previously, small Strombolian eruptions, which occurred 2-6 times/day, had occasionally ejected bombs from the 220-m-deep inner crater floor onto the main crater rim. There was little change until 13 September 1984, when a significant increase in activity occurred, peaking during September and early October but remaining at significantly higher levels than the preceding 12 years until January 1985 (9:9-10 and 10:3). From 1972 until about 1976 the lava lake expanded to a semi-circle about 60 m in diameter (figure 7, left). Erebus has been in a continuous eruptive phase since 1972, when a small anorthoclase phonolite lava lake was discovered. 3794 m All times are local (unless otherwise noted) Erebus Antarctica 77.53°S, 167.17☎ summit elev.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |