Ruapehu volcano (North Island, New Zealand): the lake temperature has decreased
Tue, 11 Aug 2020, 08:5808:58 AM | BY: MARTIN
GeoNet observatory reported that since April 2020, lake temperature has decreased from a high of 42°C to around 22-23 °C. This lower lake temperature is normal for Crater Lake. To keep the lake at this temperature, low-level heat must continue to flow into the lake. This indicates that the underlying vent area is open to volcanic gases and hydrothermal fluids. Other signs that point to this open vent are visible upwellings and sulphur slicks on the lake surface.
Ruapehu volcano today (image: GeoNet)
GeoNet volcanologists did a gas flight observations during the past three months and collected two lake samples for laboratory analysis. The results from these observations show an increase in H2S (hydrogen sulfide) gas and declines in CO2 (carbon dioxide) and SO2 gas (sulphur dioxide). This is consistent with more hydrothermal than magmatic chemical reactions in the lake.
The level of volcanic tremor intensity has been variable but weak, over the past three months. Small earthquakes continue to be located near the volcano.
Both the Volcanic Alert Level (level 1) and Aviation Code (Green) remain unchanged.
Source: GeoNet New Zealand volcano activity update 11 August 2020
Tue, 26 May 2020, 07:46
GeoNet reported that the activity at Crater Lake (Te Wai ā-moe) is often dominated by a heating-cooling cycle. These cycles last weeks-to-months. After peaking in April at 42°C, the lake cooled to 35°C by early May. Recent monitoring indicates continuous gas flux which has kept the temperature around 35°C through May. ... Read all
Mon, 4 May 2020, 06:53
GeoNet reported that during February-April, Crater Lake (Te Wai ā-moe) heated slowly to a peak temperature of 42ºC. Due to a heating-cooling cycle, there is a period of slow change before a cooling trend is clearly shown in the data. That trend is now confirmed with current temperatures close to 35ºC, with further slow cooling expected. Colour temperature is grey with a few surface slicks and no obvious upwelling. At that time the water level had dropped to about 30 cm below overflow but following this weekend's rain the lake is again overflowing into the upper Whangaehu River. ... Read all