Volcanoes menu
What is a volcano?
What are the main features of a volcano?
What are active, dormant and extinct volcanoes?
What are the different types of volcano?
What is a supervolcano?
Where are volcanoes located?
What is the Ring of Fire?
What are lahars and pyroclastic flows?
Why do people live close to volcanoes?

Case Studies
The 1980 eruption of Mount St Helens
The 1991 eruption of Mount Pinatubo
The 2000 eruption of Popocatepetl
The 2010 eruption of Eyjafjallojokull
The 2010 eruption of Mt Merapi

Related Topics
Plate tectonics
Earthquakes

What are lahars and pyroclastic flows?

What are lahars and pyroclastic flows?

What are lahars and pyroclastic flows?
The most destructive aspect of volcanoes are lahars and pyroclastic flows. Lahars are volcanic mudflows created when water (from rain or melt water from glaciers) and ash mix. This deadly combination can have devastating results on the surrounding area. When lahars settle they can be metres thick and as hard as cement. Lahars can occur long after a volcanic eruption.

Pyroclastic flows are avalanches containing hot volcanic gases, ash and volcanic bombs. On steep volcanoes pyroclastic flows can reach speeds of over 100 miles per hour.