The volcanic unrest continues to be elevated over the past four weeks.
The ongoing strong tremor is considered the longest-lived tremor over the past 20 years.
The Crater Lake (Te Wai ā-moe) temperature has decreased by 1 °C since the last measurements, but stable levels continue to keep an average 37 °C. This slowing of the heating, in spite of the ongoing strong level of volcanic tremor continues to indicate heightened volcanic unrest as the pressure could be building up at depth. The crater lake remains a battleship grey color with upwellings only at the northern vents area and no overflow. Sulfur slicks are also present on the lake surface. All these characteristics are usual for Ruapehu crater lake during a heating phase.
New Zealand’s GNS Science posted on its GeoNet site: „An observation flight and sampling of the crater lake were performed last week to further assess the activity. Our scientists observed some upwelling in the lake, indicating that hot gas and liquid are still making their way into the lake.
Our modelling suggests that about ~230 MW of heat is required to sustain this high lake temperature. Temperature and heat input remain within the typical range for a heating cycle.“
The interpretation of this activity is consistent with elevated volcanic unrest at the heightened level and therefore the Volcanic Alert Level remains at Level 2. The Aviation Colour Code remains at Yellow.
Source: GNS Science volcano activity update 19 April 2022