Sudden eruption at Krakatau volcano, Indonesia

Sudden eruption at Krakatau volcano, Indonesia

A sudden eruption took place at the Indonesian Krakatau volcano at around 07:13 UTC on October 26, 2021. The Aviation Color Code was raised to Orange.

According to Anak Krakatau Volcano Observatory, the eruption was recorded on a seismogram with a maximum amplitude of 45 mm and a maximum duration of 45 seconds.

The best ground-based estimate of ash-cloud top is around 657 m (2 102 feet) above sea level, which may be higher than what can be observed clearly.1

The Alert Level remains at 2 (on a scale of 1 - 4).

Anak Krakatau on October 16, 2021. Credit: Copernicus EU/Sentinel-2, TW

Geological summary

The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. The collapse of the ancestral Krakatau edifice, perhaps in 416 CE, formed a 7 km (4.3 miles) 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 volcanoes and left only a remnant of Rakata volcano.

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 (25 miles) 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 1927.2


1 Anak Krakatau VONA - 20211026/0720Z 

2 Krakatau - Geological summary - GVP

Featured image: CVGHM


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