Report on Krakatau (Indonesia) — July 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 7 (July 1994)
Managing Editor: Richard Wunderman.
Krakatau (Indonesia) Frequent ash explosions (300-450/day) reach heights up to 500 m
Please cite this report as:
Global Volcanism Program, 1994. Report on Krakatau (Indonesia). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 19:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199407-262000.
6.102°S, 105.423°E; summit elev. 813 m
All times are local (unless otherwise noted)
Ash explosions continued at a rate of 300-450/day in early August. The height of the ash columns, measured from the [Pasuaran Observatory] during clear weather, ranged from 150 to 500 m above the summit, with incandescent projections evident at night. The sporadic eruptions have deposited ash over almost the entire island. During the second week of August, explosion earthquakes averaged 460 events/day. Occasionally, explosion sounds were heard and vibrations felt at the observatory.
Geologic Background. The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.
Information Contacts: VSI.