Illustrated Volcano Glossary

Updated: Jun 2, 2023 05:56 GMT - refresh

pyroclastic flow: Volcanology

Pyroclastic flow travelling down the Krasak ravine at Merapi volcano on 27 May 2006.
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.

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

More on VolcanoDiscovery

La Palma Eruption </br>29 Nov - 03 Dec 21

La Palma Volcano Special
We offer a short-notice tour to see the eruption on La Palma in a small group guided by a volcanologist (Evelyne Pradal - English and French speaking geologist.)

Hawai'i

Volcano Tours on Hawai'i
The Hawaiian Islands are not only home to the most active volcanoes in the world, Kilauea and Mauna Loa on the Big Island, but also boast a unique natural environment. Born by volcanic activity of a very active hot spot in the middle of the Pacific Plate, they are a showcase of natural history.

Volcano Videos

Watch videos from our volcano trips

Cotopaxi Eruption 2015

Cotopaxi Eruption 2015 - updates
News and updates about the new eruption at Cotopaxi volcano, Ecuador, that started on 14 August 2015

Kuril Islands 17-30 July 2020

Kuril Islands expedition
The Kuril islands form one of the most active volcanic chains in the world, but are very difficult to access. From time to time, we organize expeditions to some of these remote and still unspoiled islands. Adventure guaranteed!

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:

Improved multilanguage support
Tsunami alerts
Faster responsiveness

Thanks to your past donations, these features have been added recently:

Design upgrade
Detailed quake stats
Additional seismic data sources

Download and Upgrade the Volcanoes & Earthquakes app to get one of the fastest seismic and volcano alerts online:
Android | IOS

Thank you!

Stop Russia's Agression - Support Ukraine

Significant parts of this website use brilliant open-source software developed by Ukrainians. Russia's unprovoked war has killed tens of thousands, displaced millions, and the beautiful country of Ukraine is being destroyed. We cannot be silent even if the topic of this website has nothing to do with politics.
If you like to support Ukraine from abroad:
Ukrainians recommend the Come Back Alive charity. For other options, see StandWithUkraine.

Volcanoes & Earthquakes