Mt Ruapehu kept at alert level 2 as crater take temperatures rises

Before February, the last time Mt Ruapehu was moved to volcanic level 2 was in December 2020. Photo / Geonet

Mt Ruapehu has been kept at volcanic alert level 2 as temperatures at its crater lake continue to rise.

Over the past eight days, the temperature at Mt Ruapehu's Crater Lake Te Wai ā-moe has risen further from 32C to 36C. Last month, Mt Ruapehu was moved to volcanic alert level 2 following rising temperatures at its crater lake.

GeoNet says the modelling suggests that the temperature rise corresponds to about 460 MW of heat entering the lake.

Providing an update on Ruapehu in the latest Volcanic Activity Bulletin - Crater Lake (Te Wai ā-moe) temperature and tremor levels continue to rise. Lake is now 36C and tremor remains strong. Read more: https://t.co/OIOdT2peV9 pic.twitter.com/X6TuF6B3a5

— GeoNet (@geonet) April 5, 2022

While analysis of the lake water and gas samples do not indicate significant changes, the amount of gas being released has increased but remains within observed long term trends.

The colour of the crater lake has also changed to what GeoNet has called a "battleship grey" colour as upwelling waters have disturbed sediments on the lake floor.

"The results to date are typical for the beginning of a heating cycle with the exception that tremor values are unusually high. Current data indicate that normal processes seen at the crater lake are occurring.

"Gas and fluids from the shallow magma under the volcano are interacting with the crater lake geothermal system, causing heating of the lake, volcanic tremor, and increases in gas emission at the surface."

With this in mind, GeoNet has decided to keep the Volcanic alert level at Level 2 and the Aviation Colour Code remains at Yellow.

Volcanic alert level 2 indicates the primary hazards are those expected during volcanic unrest; steam discharge, volcanic gas, earthquakes, landslides and hydrothermal activity.

While volcano alert level 2 is mostly associated with volcanic unrest hazards, eruptions can still occur with little or no warning.