The materials coming from the volcano change the landscape, sometimes rapidly, sometimes slowly. There are many types of flow, the one most talked about was the pyroclastic flows but lahars (flows mixtures of loose volcanic material and water) and surges (the violent and fast-moving part of the hot volcanic flows) also changed the landscape.

Pyroclastic flows burn vegetation, erode and destroy buildings and infrastructure as well as being a direct threat to life. This is the edge of some of the highly destructive flows on 25 June 1997. Credit: Paul Cole. Date: 25/6/1997

Lahars (Mudflows) cause rapid landscape change, particularly in the Belham Valley and around Plymouth. This is a lahar in the Belham Valley in May 2004. Credit: MVO Archive

A lahar in the Belham Valley in November 2004. The vehicle was eventually swept away. Credit: MVO Archive.