Mt Ruapehu status update: volcanic activity remains at low level, Crater Lake (Te Wai ā-moe) at 40°C

Published: Tue Apr 13 2021 10:45 AM

Volcanic Alert BulletinRUA-2021/02
Tue Apr 13 2021 10:45 AM; Ruapehu Volcano
Volcanic Alert Level remains at 1
Aviation Colour Code remains at Green

Following the period of heightened activity in December 2020, volcanic activity at Mt Ruapehu has since remained at low level over the last three months, with gas emissions, lake chemistry and volcanic tremor all within typical ranges. After a temporary cooling period, the Crater Lake (Te Wai ā-moe) temperature is now back to around 40 °C. The Volcanic Alert Level at Mt Ruapehu remains at Level 1.

In December 2020, we observed elevated unrest at Mt Ruapehu, with increased gas emissions, volcanic tremor and high lake temperatures of 43ºC. This unrest declined in January and the Volcanic Alert Level was lowered to Level 1 on 11 January 2021.

Since then we conducted two gas flights and collected lake samples twice. The results from these visits and our continuous monitoring of volcanic earthquake activity, tremor levels, and Crater Lake (Te Wai ā-moe) temperature and level indicate that key parameters remain within normal ranges. The largest observed variation has been with the crater lake water temperature. This was over 43ºC in early January 2021 then cooled to 26ºC on 15 February. It has now reheated to 40ºC. To maintain the lake water temperature at around 40ºC our modelling indicates that ~400 MW (megawatt) of heat is still entering the lake.

All these observations suggest that volcanic activity remains at low level at Mt Ruapehu.

The Volcanic Alert Level remains at Level 1 which reflects the current level of volcanic unrest. Mt Ruapehu is an active volcano and has the potential to erupt with little or no warning when in a state of volcanic unrest. The Aviation Colour Code remains at Green.

The Volcanic Alert Level should not be used to forecast future activity, however at Volcanic Alert Level 1, eruptions are less likely than at Volcanic Alert Level 2.

Volcanic Alert Level 1 indicates the primary hazards are those expected during volcanic unrest: steam discharge, volcanic gas, earthquakes, landslides and hydrothermal activity. While Volcanic Alert Level 1 is mostly associated with environmental hazards, eruptions can still occur with little or no warning. For information on access to the Mt Ruapehu area, please visit the Department of Conservation’s websites on volcanic risk in Tongariro National Park and follow their Facebook page for further updates.

GNS Science and the National Geohazards Monitoring Centre continue to closely monitor Mt Ruapehu for further changes.

Yannik Behr Duty Volcanologist Media Contact: 021 574 541 or media@gns.cri.nz