Changes in ash composition can give us important clues about the activity of volcanoes. The thickness of the deposit and type of ash also provides information about the size and style of an eruption. It is also important to ensure the ash is not hazardous to health. That’s why, at times when everyone on island was struggling to rid their homes of ash, scientists regularly went out and collected ash samples to analyse their composition.

Scientist wearing an orange boiler suit walks down a hillside covered by ashes from the eruption of Soufrière Hills in 1997. Credit: Barry Lewis / Alamy.
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4. Falling ash and stones
Ballistics1996
1997
2000 +
East
The Volcano & Belham
West (Plymouth)