Glossary
Lahar
A lahar is a volcanic mudflow made of water, ash and debris. It forms when an eruption melts snow or a glacier, or when heavy rain remobilises ash.
Lahars follow valleys and can travel tens of kilometres, far beyond the areas threatened by the eruption itself. In 1985, a lahar from Nevado del Ruiz in Colombia buried the town of Armero and killed more than 20,000 people.
Examples on the Map
Other Definitions
- Tectonic Plate
- Subduction
- Mid-Ocean Ridge
- Transform Fault
- Fault
- Earthquake, Epicentre and Hypocentre
- Magnitude
- Intensity (Mercalli Scale)
- Aftershock
- Tsunami
- Active Volcano
- Stratovolcano
- Shield Volcano
- Caldera
- Volcanic Explosivity Index (VEI)
- Pyroclastic Flow
- Hotspot
- Tropical Cyclone, Hurricane, Typhoon
- Saffir-Simpson Scale
- Aurora and Kp Index