Report on Krakatau (Indonesia) — April 1980
Scientific Event Alert Network Bulletin, vol. 5, no. 4 (April 1980)
Managing Editor: David Squires.
Krakatau (Indonesia) Explosions eject incandescent tephra
Please cite this report as:
Global Volcanism Program, 1980. Report on Krakatau (Indonesia). In: Squires, D. (ed.), Scientific Event Alert Network Bulletin, 5:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198004-262000.
6.102°S, 105.423°E; summit elev. 813 m
All times are local (unless otherwise noted)
Activity began to increase at the end of March. Detonations from explosions were heard 50 km away and window glass trembled on the W coast of Java. Incandescent material rose 200 m above the vent, which approximately coincided with the 1975 eruption center. About 65 explosion events were recorded on 13 April, and 290 on 16 April. The strongest activity occurred during a 5-hour period on 19 April, when 200 explosions were recorded. There were 335 explosions on 20 April, but activity was declining the next day. Rough seas prevented a landing on the island.
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, L. Pardyanto, and Suparto S., VSI.