Report on Krakatau (Indonesia) — December 1979
Scientific Event Alert Network Bulletin, vol. 4, no. 12 (December 1979)
Managing Editor: David Squires.
Krakatau (Indonesia) Eruption ends
Please cite this report as:
Global Volcanism Program, 1979. Report on Krakatau (Indonesia) (Squires, D., ed.). Scientific Event Alert Network Bulletin, 4:12. Smithsonian Institution.
6.102°S, 105.423°E; summit elev. 155 m
All times are local (unless otherwise noted)
The average number of eruption tremors/day recorded at Pasauran, 30 km from the volcano, was 70 in July, 50 in August, and 100 in September, then dropped sharply to two in October and November. No tremors were recorded in December, and detonations and ejection of incandescent materials were no longer observed.
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: A. Sudradjat, VSI; Suparto S., Java and Sumatra Observatory, VSI.