Tue, 11 Aug 2020, 08:58
Ruapehu volcano today (image: GeoNet)
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.
...moreGeoNet 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. [
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Tue, 26 May 2020, 07:46
Ruapehu volcano today (image: GeoNet)
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. ...moreSulfur dioxide (SO2) emissions remains steady. Carbon dioxide (CO2) emissions have increased.
It indicates that the underlying vent area is open to upflows of volcanic gases and hydrothermal fluids, and so is currently preventing the lake from cooling further. Other signs that point to an open vent status are visible upwellings and sulphur slicks on the lake surface. None of these observations are unusual for the volcano. [
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Mon, 4 May 2020, 06:53
Crater Lake at Ruapehu volcano (image: @geonet/twitter)
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.
...moreThe volcanic tremor intensity is weak, as it has been during the past month. After a peak of moderate strength in early March, the tremor declined slowly, almost in parallel to the lake’s cooling trend.
The volcano is still a very active volcano with the potential of little or no warning. [
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Fri, 20 Mar 2020, 05:56
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.
...moreIn 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. [
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Tue, 3 Mar 2020, 08:17
Ruapehu volcano today (image: GeoNet)
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.
...moreThe amounts of
carbon dioxide (CO2) and sulphur gases (SO2 and H2S) have increased since the last measurements on 7th February 2020. Water samples are being analysed this week, with chemistry results expected by next week.
New analysis of last week’s volcanic earthquakes defines a source area 3 km beneath the summit of the volcano, which is normal for seismic activity at Ruapehu.
Volcanic tremor increased in strength briefly last weekend, then declined during the week, and has now
increased again to similar levels. [
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Mon, 24 Feb 2020, 07:27
Ruapehu volcano today (image: Geonet)
GeoNet reported that seismographs detected
a sequence of seismic events beneath Mt Ruapehu
during 22-23 February. GNS Science volcanologists have categorised them as volcanic earthquakes. The larger events at the start of the episode are approximately magnitude 1.5 and later, smaller events are too small to be located by GeoNet’s earthquake detection-location system.
...moreThe seismic recordings indicate a source beneath the summit area, which is normal for volcanic earthquakes and volcanic tremor at Ruapehu.
The earthquake episode has ended.The Crater Lake (Te Wai ā-moe) temperature has been around 24-25 ºC for the last few months. It is not unusual to observe volcanic earthquakes on Ruapehu and other episodes of increased seismic activity were observed during March 2018, April 2016 and September 2017. None of these resulted in a sustained increase in volcanic unrest. [
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Wed, 15 Jan 2020, 09:30
Ruapehu volcano today (image: Geonet)
GeoNet reported that the activity of volcanic tremor continues at low levels. Measurements of the volcano’s Crater Lake (Te Wai ā-moe) temperature, and chemistry remained consistent in combination with
seismic unrest. ...moreRegular gas flights and lake sampling are also undertaken as weather permits.
Since the last measurements lake temperatures have cycled around
22°C-28°C. For the last 10 years temperatures of the summit crater lake have cycled around 25°C. [
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