Mt Ruapehu (North Island, New Zealand):increasing crater lake temperature
GNS Science Volcanologists have collected water samples from Crater Lake (Te Wai ā-moe) and the temperature of the lake is now 40°C. GeoNet believe the heating of the lake is the response to an input of hot gases and hydrothermal fluids in the wake of volcanic earthquakes beneath Mt Ruapehu in February. Prior to the earthquakes, the lake measured 24ºC.
Fri, 20 Mar 2020, 05:5605:56 AM | BY: MATTHEW
In the last report, we noted that the GeoNet volcanologist reported “an upwelling of grey sediment and sulphur slicks on the lake surface.” Now the lake is well mixed and has changed to a uniform grey colour. The continued flow of gases and hydrothermal fluids through the lake show that the volcano's vent underlying Crater Lake is open.
GeoNet report that the lake is overflowing at the outlet channel, with a notable decrease in the flow rate between their last two visits. Also, volcanic tremor increased in response to the volcanic earthquakes, peaking in early March, then declined slowly until today. Modelling of the energy input into the lake shows that the heat input increased from around 200 MW to around 600 MW but has now declined as the temperature rise has slowed. Heating cycles such as this are very common at Ruapehu.
The amounts of carbon dioxide (CO2) and sulphur gases (SO2 and H2S) in the atmosphere above the volcano measured on 28 February was greater than when measured on 7 February. However, the recent values are not unusual and are within the ranges measured over the past year.
The Volcanic Alert Level remains at Level 1. The Volcanic Alert Level reflects the current level of volcanic activity and is not a forecast of future activity. Mt Ruapehu is an active volcano and has the potential to erupt with little or no warning when in a state of volcanic unrest. There is no change in the Aviation Colour Code from Green.
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Links / Sources:
Tue, 3 Mar 2020, 08:17
GeoNet volcanologists have collected water samples from Crater Lake and measured volcanic gases in the plume last week. Seismic data have been analysed in detail. ... Read all