Report on Krakatau (Indonesia) — March 1995
Bulletin of the Global Volcanism Network, vol. 20, no. 3 (March 1995)
Managing Editor: Richard Wunderman.
Krakatau (Indonesia) Explosions continue, sending ash plumes daily up to 500 m above the summit
Please cite this report as:
Global Volcanism Program, 1995. Report on Krakatau (Indonesia). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 20:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199503-262000.
6.102°S, 105.423°E; summit elev. 813 m
All times are local (unless otherwise noted)
Volcanic activity continued through January-March 1995, sending grayish white plumes 150-500 m above the summit. Sounds like thunder were sometimes heard at the VSI observatory . . . and glow was visible at night as high as 50 m above the summit. The daily number of explosions in January and early February fluctuated between 50 and 150 events. From mid-February to mid-March the average number of explosions increased to 150-200 events/day (figure 10).
|Figure 10. Daily number of explosion earthquakes (bars) and height of the ash plume (line) at Krakatau, January-March 1995. Courtesy of VSI.|
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: W. Tjetjep, VSI.