The raw power of the lahar (a volcanic landslide) – a new video of three lahars from Japan

Lahars are extraordinarily energetic debris flows that originate in volcanic materials.  They are one of the most poorly understood volcanic processes, even though they are exceptionally destructive.  Lahars have been responsible for thousands of deaths in the last century – the 1985 lahar from Nevado del Ruiz in Colombia is believed to have killed over 23,000 people for example.  Those sorts of numbers are hard to believe unless you have seen the nature of these landslides.  To this end, a new video has appeared on Youtube showing footage from three lahar events in Japan.  All appear to have occurred in the 1990s.  The third in the sequence is probably the most impressive (and is the source of the screenshot above):