On Saturday 11 August GNS Science advised of the potential for mud and debris flows in the northern Tongariro area given the forecasted heavy rain. Rain-triggered mudflows (lahars) are common on volcanoes following eruptions, due to the presence of loose ash and debris in stream catchments.

Following heavy rainfall yesterday morning (Sunday 12 August), flows of muddy sediment-rich water crossed State Highway 46, approximately 6 km west of Rangipo. Taupo District emergency management teams responded to the situation. Scientific research teams from Massey University travelled to the area to record the flow characteristics and inspect other streams and stream channels. Further information will be reported as it becomes available.

Monitoring of Tongariro volcano continues and updates will be issued should the situation change.

An ashfall prediction plot attached to this bulletin shows the area where ash is likely to fall within the next six hours, should an eruption occur.

Michael Rosenberg Duty Volcanologist