(Image: USGS)
It must have been terrifying to be in Oso, Washington, on 22 March, when heavy rains turned a previously stable mix of rock, sand and clay into an 8-million-cubic-metre wall of moving liquid. On its 1-kilometre journey it briefly dammed a river, obliterated a neighbourhood, buried a stretch of highway and killed at least 35 people.
. It should not have gone so far, given the height from which it travelled. However, landslides above a certain size .
Advertisement
To gain insight into the catastrophe, Richard Iverson of the US Geological Survey鈥檚 Cascades Volcano Observatory in Vancouver, Washington, decided to model it.
The covers 10 minutes, but you can see from this animation that most of the material travelled more than a kilometre in about 90 seconds. The top speed is estimated at almost 100 kilometres per hour. This is the first opportunity to look at it as it happened in real time.
If we can use work like this to identify unstable slopes, acoustic sensor systems currently under development could be deployed on to provide early warning of landslides.
