Geologic Background:
This renowned volcano lies in the Sunda Strait
between Java and Sumatra. Caldera collapse, perhaps in
416 A.D., destroyed the ancestral Krakatau edifice,
forming a 7-km-wide caldera. Remnants of this volcano
formed Verlaten and Lang islands; subsequently Rakata,
Danan, and Perbuwatan volcanoes formed, coalescing into
pre-1883 Krakatau Island. Caldera collapse during the
1883 eruption destroyed Danan and Perbuwatan, leaving a
remnant of Rakata. The post-collapse cone of Anak
Krakatau (Child of Krakatau) is located within the 1883
caldera between the former Danan and Perbuwatan cones.
Historic Activity:
- Anak Krakatau (child of Krakatau) is a small cone
that has been growing near the center of Krakatau's
(1883) caldera since 1927.
- During the 7 previous eruptions that produced lava
(1958-63, 1965, 1972-3, 1975, 1979, 1980, and 1988),
flows moved south and southwest from the southwest
crater.
Recent Activity:
- During February 1988 dark ash plumes rose a few
hundred meters above the new crater and a glow was
reported on March 1. Two small lava flows from the new
crater were reported on March 16. Eruption has continued
through April 1988 with frequent explosions ejecting
small plumes.
- An eruption began on Nov. 7, 1992 from Anak
Krakatau's northeast crater. The strongest explosive
activity occurred on Nov. 12, 1992. Bombs fell to several
hundred meters north of the vent and smaller tephra
reached the north coast. Lava flowed 1 km to the north
coast and entered the sea, extending more than 100 m
beyond the former shore. Lava continued to advance in
January, but feeding of the flow from the vent may have
stopped by mid-February. New flows began in February and
have continued in to July 1993. Explosive activity at the
crater killed a tourist and injured 5 others climbing the
old crater rim. Observers on W Java noted that lava
glowed strongly in early May but had stopped by mid-June.
As of Aug. 14 glowing had not reappeared.
- After 5 months of quiet, activity apparently began
again on March 19, 1994. At the end of March, thick black
ash plumes rose 300 m while "red flames and glowing lava"
were observed at night. A reported eruption on May 5,
ejected lava 200 m into the air. Ash explosions continued
at a rate of 300-450/day in early August. Reports of ash
clouds by airline pilots on Oct. 16, Nov. 28, and Dec.
18, 1994. Continued explosions and ash clouds through
June 1995.
- Continuing activity from 1997 to 2001.
Data Sources:
- Smithsonian's SEAN Bulletin (V. 3, No. 7 to V. 13,
No. 4)
- Global Volcanism Network (V. 17, No. 10 to V. 26, No.
9).
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