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Report on Krakatau (Indonesia) — 20 May-26 May 2015


Krakatau

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 20 May-26 May 2015
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2015. Report on Krakatau (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 20 May-26 May 2015. Smithsonian Institution and US Geological Survey.

Weekly Report (20 May-26 May 2015)

Krakatau

Indonesia

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

All times are local (unless otherwise noted)


PVMBG reported that during 22 April-25 May diffuse white plumes rose 25 m above Anak Krakatau, although foggy weather often prevented observations. Seismicity was high during May, and continued to be dominated by shallow and deep volcanic earthquakes, and signals indicating emissions. 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.

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