Report on Krakatau (Indonesia) — October 1979
Scientific Event Alert Network Bulletin, vol. 4, no. 10 (October 1979)
Managing Editor: David Squires.
Krakatau (Indonesia) Oblique airphoto of September activity
Please cite this report as:
Global Volcanism Program, 1979. Report on Krakatau (Indonesia) (Squires, D., ed.). Scientific Event Alert Network Bulletin, 4:10. Smithsonian Institution.
6.102°S, 105.423°E; summit elev. 155 m
All times are local (unless otherwise noted)
An eruption of Anak Krakatau began in mid-July from the 1978 crater (see figures 1 and 2), ejecting tephra and extruding lava that flowed into the sea at the island's W coast. Lava extrusion had ended by early September, but tephra emission continued at varying levels of intensity through the end of the month.
|Figure 2. Oblique airphoto of Anak Krakatau, 12 September 1979, looking approximately NW. Verlaten Island (caldera rim) is in the background. An eruption column rises from the 1978 crater. Photo taken by Maurice Krafft.|
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: Maurice Krafft, Cernay, France.