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Report on Krakatau (Indonesia) — August 2003


Bulletin of the Global Volcanism Network, vol. 28, no. 8 (August 2003)
Managing Editor: Edward Venzke.

Krakatau (Indonesia) Continued shallow volcanic seismicity through mid-August

Please cite this report as:

Global Volcanism Program, 2003. Report on Krakatau (Indonesia) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 28:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200308-262000



6.1009°S, 105.4233°E; summit elev. 285 m

All times are local (unless otherwise noted)

Due to continued foggy weather, no visual observations could be made at Krakatau during July and through 17 August. Throughout this period the volcano remained at Alert Level 2. Seismicity reported by the Volcanological Survey of Indonesia (VSI) between 30 June and 17 August consisted mostly of shallow volcanic events (table 4), although 36 deep volcanic earthquakes were recorded during the week of 30 June-6 July.

Table 4. Seismicity at Krakatau, 30 June-17 August 2003. Courtesy of VSI.

Date Deep volcanic (A-type) Shallow volcanic (B-type) Tectonic
30 Jun-06 Jul 2003 36 123 9
07 Jul-13 Jul 2003 5 112 13
14 Jul-20 Jul 2003 4 28 8
21 Jul-27 Jul 2003 8 33 6
28 Jul-03 Aug 2003 7 37 2
04 Aug-10 Aug 2003 6 25 4
11 Aug-17 Aug 2003 2 22 8

Geological Summary. The renowned Krakatau (frequently mis-named as Krakatoa) volcano lies in the Sunda Strait between Java and Sumatra. Collapse of an older edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of that volcano are preserved in Verlaten and Lang Islands; subsequently the Rakata, Danan, and Perbuwatan cones 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 caused more than 36,000 fatalities, most as a result of 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 Danan and Perbuwatan cones. Anak Krakatau has been the site of frequent eruptions since 1927.

Information Contacts: Dali Ahmad and Nia Haerani, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi. esdm.go.id/).