Mt. Ruapehu’s crater lake is at its hottest temperature since 2003.
Tuesday 8th March 2011
Ruapehu’s crater lake entered a heating cycle in October 2010, as the hydrothermal system became more active. Small changes in the chemistry of the lake and minor seismic activity have been associated with the change. The lake has now reached 40 ºC, the third highest temperature recorded since the lake was re-established in 2002, following the eruptions of 1995 and 1996.
There have been eight distinctive heating cycles since the lake was re-established, reaching a maximum temperature of 42.5 ºC in May 2003.
Monitoring of gas output, seismic activity, lake chemistry and ground deformation have shown variable trends in recent weeks, typical behaviour for Ruapehu during a lake heating cycle.
The current activity could result in the lake temperature continuing to rise, and the lake colour may change if lake-floor sediments are disturbed. In the right atmospheric conditions, steam may also be seen above the crater lake.
The latest observations are within the normal range for Mt. Ruapehu and the alert level for the volcano remains at 1 (signs of unrest). In reporting the change, vulcanologists point out that Ruapehu remains an active volcano, and future eruptions may occur without warning.
[ Compiled from GNS Science Volcanic Alert Bulletin RUA-2011/01 issued March 7th. ]