Topic summary
Lahars
Extracted from the Wikipedia article Lahar.
Description
Lahars vary in speed. Small lahars less than a few metres wide and several centimetres deep may flow a few metres per second. Large lahars hundreds of metres wide and tens of metres deep can flow several tens of metres per second (22 mph or more), much too fast for people to outrun. On steep slopes, lahar speeds can exceed 200 kilometres per hour (120 mph). A lahar can cause catastrophic destruction along a potential path of more than 300 kilometres (190 mi).