The eruption of Indonesia’s Mount Sinabung, which shot ash five kilometres (three miles) high, also “annihilated” the mountain’s summit.
Before and after images from Indonesia’s Centre for Volcanology and Geological Hazard Mitigation show an enormous chunk missing from the peak.
Volcanologist Devy Kamil Syahbana said the chunk, known as the “lava dome”, had a volume of at least 1.6 million cubic metres (56.5 million cubic feet).
The volcano in North Sumatra, which has been active since 2010, erupted explosively on Monday morning.
Hot ash clouds rolled down its slopes, travelling as far as 4.9 kilometres from the crater.
Video showed screaming children fleeing a school outside the exclusion zone that surrounds the volcano as a billowing column of ash rose in the background.
No-one was injured.
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