Mount Erebus (3,794 meters), the world's southernmost historically active volcano, overlooks the McMurdo research station on Ross Island. Erebus is the largest of three major volcanoes forming the crudely triangular Ross Island. The summit has been modified by several generations of caldera formation. A summit plateau at about 3,200 meters altitude marks the rim of the youngest caldera, within which the modern cone was constructed. An elliptical 500 x 600 meter wide, 110-meter-deep crater truncates the summit and contains an active lava lake within a 250-meter-wide, 100-meter-deep inner crater. The glacier-covered volcano was erupting when first sighted by Captain James Ross in 1841. Continuous lava-lake activity has been documented since 1972, punctuated by occasional strombolian explosions that eject bombs onto the crater rim.
Mount Erebus is an intraplate volcano, situated at the southern end of the Terror Rift within the Victoria Land basin, a major sedimentary basin with over 12 kilometers of fill and underlain by 21-kilometer-thick crust. The basin is bounded to the west by the Transantarctic Mountains, with 40-kilometer-thick curst (Cooper and Davey, 1985; Fitzgerald and others, 1986).
An older cone of Mount Erebus (Fang Volcano), composed largely of benmoreite, was partly destroyed by an unknown event, leaving a caldera of about 6-kilometers diameter. The modern cone of Mount Erebus, composed largely of anorthoclase phonolite (Kyle, 1977), has largely filled the older caldera, leaving only Fang Ridge (north of Mount Erebus) as a relic of the older cone. A roughly 5-kilometer-diameter caldera developed at the top of the modern cone, and it too has been largely filled (Berninghausen and Neumann van Padang, 1960; P. Kyle, written commun., 1987).
Most historical activity has been confined to the younger caldera. A reported exception was increased fumarolic activity in April-September 1908 and on 17 June 1908, near Abbot Peak, 10 kilometers north-northeast of the summit of Mount Erebus (cited in Berninghausen and Neumann van Padang, 1960). A seismic swarm in roughly the same area was recorded in October 1962 (Ueki and others, 1984; Kaminuma and others, 1985).
A lava lake discovered in 1972 grew slowly until 1976, when it was circular, about 60 meters in diameter. It remained relatively constant until September 1984. Larger-than-usual Strombolian explosions occurred in September to December 1984. Earthquakes were felt, and glow and increased steaming were observed from McMurdo Sound (37 kilometers southwest of the volcano) (P. Kyle and others, in Smithsonian Institution, 1984). The summit crater lava lake was buried by ejecta between 13 September 1984 and October 1984. When the lake was exhumed in December 1985 it was 15 meters in diameter, and it grew to 20 meters in diameter by December 1986 (P. Kyle, written commun., 1987).
Mount Erebus is an intraplate volcano, situated at the southern end of the Terror Rift within the Victoria Land basin, a major sedimentary basin with over 12 kilometers of fill and underlain by 21-kilometer-thick crust. The basin is bounded to the west by the Transantarctic Mountains, with 40-kilometer-thick curst (Cooper and Davey, 1985; Fitzgerald and others, 1986).
An older cone of Mount Erebus (Fang Volcano), composed largely of benmoreite, was partly destroyed by an unknown event, leaving a caldera of about 6-kilometers diameter. The modern cone of Mount Erebus, composed largely of anorthoclase phonolite (Kyle, 1977), has largely filled the older caldera, leaving only Fang Ridge (north of Mount Erebus) as a relic of the older cone. A roughly 5-kilometer-diameter caldera developed at the top of the modern cone, and it too has been largely filled (Berninghausen and Neumann van Padang, 1960; P. Kyle, written commun., 1987).
Most historical activity has been confined to the younger caldera. A reported exception was increased fumarolic activity in April-September 1908 and on 17 June 1908, near Abbot Peak, 10 kilometers north-northeast of the summit of Mount Erebus (cited in Berninghausen and Neumann van Padang, 1960). A seismic swarm in roughly the same area was recorded in October 1962 (Ueki and others, 1984; Kaminuma and others, 1985).
A lava lake discovered in 1972 grew slowly until 1976, when it was circular, about 60 meters in diameter. It remained relatively constant until September 1984. Larger-than-usual Strombolian explosions occurred in September to December 1984. Earthquakes were felt, and glow and increased steaming were observed from McMurdo Sound (37 kilometers southwest of the volcano) (P. Kyle and others, in Smithsonian Institution, 1984). The summit crater lava lake was buried by ejecta between 13 September 1984 and October 1984. When the lake was exhumed in December 1985 it was 15 meters in diameter, and it grew to 20 meters in diameter by December 1986 (P. Kyle, written commun., 1987).
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