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Report on Krakatau (Indonesia) — 14 November-20 November 2018


Krakatau

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 14 November-20 November 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, 14 November-20 November 2018. Smithsonian Institution and US Geological Survey.

Weekly Report (14 November-20 November 2018)

Krakatau

Indonesia

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

All times are local (unless otherwise noted)


PVMBG reported that seven events at Anak Krakatau were recorded between 0840 on 14 November and 0601 on 15 November. Each event lasted for 33-175 seconds, based on the seismic data, and produced ash plumes that rose 0.3-1 km above the crater rim and drifted N, ENE, and E. A 212-second-long event at 0524 on 16 November generated a dense black ash plume that rose 600 m and drifted NE. An event at 0532 lasted 207 seconds and generated an ash plume that rose 300 m and drifted NE. The Alert Level remained at 2 (on a scale of 1-4); residents and visitors were warned not to approach the volcano within 2 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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)