Mt Ruapehu

[David]

Volcanic alert level raised to 2 http://info.geonet.org.nz/display/volc/ ... to+Level+2

Recent visits to the volcano have confirmed an increase in the output of volcanic gas from Mt Ruapehu’s Crater Lake. Moderate levels of volcanic tremor continue and the lake temperature measured by the outlet data logger is 45 ºC. The increase in gas output, the high lake temperature and continued seismicity suggest that Ruapehu is at a higher level of volcanic unrest. As a result, GNS scientists revise the Volcanic Alert Level to Level 2 (moderate to heightened unrest). The Aviation Colour Code is also changed, from Green to Yellow.

[David]

An increase in volcanic tremor just now, looking at the drums http://www.geonet.org.nz/volcano/info/ruapehu/drums

[ScottyD]

An increase in volcanic tremor just now, looking at the drums http://www.geonet.org.nz/volcano/info/ruapehu/drums

I'm wondering if that is just wind noise on the far west drum, as the wahianoa drum hasn't changed much.

[David]

Yeah, that is possible looking at the RSAM/SSAM plots now. They key to wind noise is if the warmer colours extend up to the top of the chart. Earlier I couldn't see that, but now it looks like that may be the case.

[Cyclone Tracy]

GeoNet have had a couple of updates in the last few weeks.

https://www.geonet.org.nz/vabs/3YlHGHxZqdfLRvfoibsQg3
https://www.geonet.org.nz/vabs/1BpMvvfgfDm7kZH7gYIWvL

Then I noticed one of the drum on a low scale is showing a continuous harmonic tremor this morning. Might be worth keeping an eye on.

[Awhituobs]

wind can do that

[David]

Yeah I think that's wind - if you look at the RSAM/SSAM graph the warmer colour goes all the way up the frequency band (compare to White Island where it's concentrated in the 5-10 Hz range, which is in the usual range for volcanic tremor)

[Cyclone Tracy]

I was more focusing on the clips within the continuous enhanced signal. So you are saying the wind caused the seismogram be to be clipped (red signal) during this phase? There are 2 clips in the last 6 hours. I would assume one of those clips was this one https://www.geonet.org.nz/earthquake/2020p169806

[Cyclone Tracy]

Ruapehu's earthquake monitor now showing a microquake at 1.41pm today 6km beneath the summit and next to the 22/23 Feb quakes talked about by GeoNet's last report 2 days ago.

[David]

The clipped parts are probably nearby quakes yes, just referring to the continuous lower intensity signal which appears to be wind noise

[tornado]

ruapehu has been showing signs of activity lately. just hope if there is a eruption not many people would be on it. but it is a popular site . perhaps if activity increase a warning should be put out.

[Cyclone Tracy]

Crater Lake is now 40c. GeoNet also confirming the increased volcanic tremor in early March. "Volcanic tremor increased in response to the volcanic earthquakes, peaking in early March, then declined slowly until today"

https://www.geonet.org.nz/vabs/7CzClDxM8DzsD1K41Zay6M

[Cyclone Tracy]

2nd day in row a sequence of protracted harmonic tremor activity is being picked up by the low scale drum.

[David]

I dunno, the frequency looks rather high on the RSAM/SSAM, 15+ Hz. The signal on the drum (in your post) does look seismic though (too intermittent for wind noise)

[Cyclone Tracy]

Yes agree, I think we can rule out wind. The long seismic wave from this morning is harmonic with no clear / sharp P and S waves. It has a volcanic signature to it but as you say the frequency doesn't look as convincing.

[Cyclone Tracy]

GeoNet have raised the volcanic alert level to 2 - https://www.geonet.org.nz/vabs/2eRQvDWg31q0luE4H2McoY

[tornado]

GeoNet have raised the volcanic alert level to 2 - https://www.geonet.org.nz/vabs/2eRQvDWg31q0luE4H2McoY

Yes. I see that. Interesting.

[Cyclone Tracy]

A gradual increase in harmonic tremor over the last 18 hours on the lower scale drum.

[Razor]

A gradual increase in harmonic tremor over the last 18 hours on the lower scale drum.

Could also be wind interference given the weather currently up there

[David]

A gradual increase in harmonic tremor over the last 18 hours on the lower scale drum.

Could also be wind interference given the weather currently up there

That's how I interpreted it too

[Cyclone Tracy]

Yes, I agree. Wind the culprit from the north and and now west with other nearby low scale drums clearly in a more protected environments with those prevailing winds.

[David]

Pretty sure that's stronger tremor over the last day or so showing on the drum, frequency <10Hz

[Cyclone Tracy]

2 small seismic quakes under the crater early this morning.

[David]

Strong signal on the drums around 7pm for about 3 mins. Looks like it's from a magnitude 2.2 volcanic earthquake 3km below the crater... This is getting more interesting

[David]

Geonet update
https://www.geonet.org.nz/vabs/2QEbIuTTybQJ2wzdrveMzk

Mt Ruapehu Crater Lake temperature down to 41 ̊C but volcanic tremor still elevated

During the past week, the temperature of the crater lake (Te Wai ā-moe) at Mt Ruapehu has decreased from 43 to 41 °C. The level of volcanic tremor continues to be moderate to strong and a small number of shallow volcanic earthquakes have been recorded. While the crater lake may have stopped heating, volcanic activity at Mt Ruapehu remains elevated. The Volcanic Alert Level remains at Level 2 and the Aviation Colour Code remains at Yellow.

Since our last update (VAB RUA - 2020/10), Ruapehu’s Crater Lake (Te Wai ā-moe) temperature has decreased slightly. The temperature reached a maximum of 43 ºC on Monday 21st December that subsequently declined to ~41 ºC. A lake temperature peak of ~ 40-46 ºC is common during these heating-cooling cycles; on at least 7 occasions since 2007, the lake temperature exceeded 40 ºC. Using this lake temperature decrease, we estimate that the energy input into the lake has decreased from ~400 to ~200 MW (megawatt).

Elevated volcanic tremor is still ongoing along with a few volcanic earthquakes. The largest of these earthquakes (M2.2) occurred on 26th December and was located under the volcano. Volcanic earthquakes of this size are uncommon and the combination with elevated tremor and still high lake temperature indicate moderate to heightened volcanic unrest. Because of this, the Volcanic Alert Level remains at Level 2.

We continue to closely monitor Ruapehu, and this week we will attempt a gas flight to measure volcanic gas emissions. We will also attempt to sample the water at the crater lake for further chemical analyses. Together, these will help us identify processes occurring at depth beneath the volcano.

The Volcanic Alert Level is still at Level 2 which reflects the current level of volcanic 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. The Aviation Colour Code remains at Yellow.

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

Volcanic Alert Level 2 indicates the primary hazards are those expected during volcanic unrest: steam discharge, volcanic gas, earthquakes, landslides and hydrothermal activity. While Volcanic Alert Level 2 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 website or follow DOC’s Facebook page for further updates.

GNS Science and the National Geohazards Monitoring Centre continue to closely monitor Mt Ruapehu for further changes in unrest. GeoNet monitors Mt Ruapehu via a network of seismic and acoustic sensors, GNSS (GPS) receivers, sensors in the lake and visits to the lake area and gas flights.