Illustrated Volcano Glossary

pyroclastic flow

Volcanology
Pyroclastic flow travelling down the Krasak ravine at Merapi volcano on 27 May 2006.
Pyroclastic flow travelling down the Krasak ravine at Merapi volcano on 27 May 2006.
The billowing ash could of the advancing pyroclastic flow.
The billowing ash could of the advancing pyroclastic flow.
Merapi seen from the area of Kaliadem with the fresh deposits of a pyroclastic flow (June 06) in the foreground. This flow killed two people trapped inside a bunker that became buried under the hot deposit.
Merapi seen from the area of Kaliadem with the fresh deposits of a pyroclastic flow (June 06) in the foreground. This flow killed two people trapped inside a bunker that became buried under the hot deposit.
Fluid avalanche of turbulently mixed ash, lava and or rock fragments, and air, that flows down the flanks of a volcano, driven by gravity. Pyroclastic flows are usually very hot and highly destructive.
A pyroclastic flow is a ground-hugging avalanche of hot ash, pumice, rock fragments, and volcanic gas that rushes down the side of a volcano as fast as 100 km/hour or more. The temperature within a pyroclastic flow may be greater than 500°C, sufficient to burn wood. Once deposited, the ash, pumice, and rock fragments may deform (flatten) and weld together because of the intense heat and the weight of the overlying material.
Facts and figures:
On 8. May 1902 a pyroclastic flow from Montagne Pelée, Martinique, caused the worst volcanic disaster of the 20th century. 28'000 people perished in the city of St. Pierre, located 7 km from the volcano's summit

Related keywords (4):

ash - base surge - debris avalanche - explosive
Try our free app!
Volcanoes & Earthquakes - new app for Android
Android | iOS version

More on VolcanoDiscovery

Why is there advertising on this site?
Support us - Help us upgrade our services!
We truly love working to bring you the latest volcano and earthquake data from around the world. Maintaining our website and our free apps does require, however, considerable time and resources.
We need financing to increase hard- and software capacity as well as support our editor team. We're aiming to achieve uninterrupted service wherever an earthquake or volcano eruption unfolds, and your donations can make it happen! Every donation will be highly appreciated. If you find the information useful and would like to support our team in integrating further features, write great content, and in upgrading our soft- and hardware, please make a donation (PayPal or Online credit card payment).

Planned features:
  • Weather reports
  • Tsunami alerts
  • Design upgrades
  • Faster responsiveness
Thanks to your past donations, these features have been added recently:
  • Earthquake archive from 1900 onwards
  • Additional seismic data sources
  • Improved content in English
Download and Upgrade the Volcanoes & Earthquakes app to get one of the fastest seismic and volcano alerts online:
Android | IOS
Thank you!
Copyrights: VolcanoDiscovery and other sources as noted.
Use of material: Most texts and images, in particular photographs, on this website are protected by copyright. Further reproduction and use of without authorization is usually not consented. If you are not sure or need licensing rights for photographs, for example for publications and commercial use, please contact us.