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Report on Krakatau (Indonesia) — 25 July-31 July 2018


Krakatau

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 25 July-31 July 2018
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2018. Report on Krakatau (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 25 July-31 July 2018. Smithsonian Institution and US Geological Survey.

Weekly Report (25 July-31 July 2018)

Krakatau

Indonesia

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

All times are local (unless otherwise noted)


Based on satellite and wind model data, the Darwin VAAC reported that during 25-26 July minor ash plumes from Anak Krakatau rose to an altitude of 1.2 km (4,000 ft) a.s.l. and drifted SW and NW. PVMBG noted that inclement weather conditions prevented views of the volcano during 27-30 July. The Alert Level remained at 2 (on a scale of 1-4); residents and visitors were warned not to approach the volcano within 1 km of the crater.

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.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC)