Unrest Continues at Mt. Ruapehu

Increased gas output and continued high lake temperatures at Mt. Ruapehu show that the volcano has continued to be active since its last eruption.

Mt. Ruapehu’s crater lake has remained hot since the volcano’s last eruption in September last year. The temperature of the lake has fluctuated between 34 ºC and 37 ºC and, when last measured on June 12th, was at 35.2 ºC.

Analysis of the plume of gases above the volcano shows that sulphur dioxide has gradually increased since last year’s eruption and carbon dioxide levels have varied. The emission rates of both gases have shown significant increases since April, being about 10 times above typical levels.

The increased temperatutres and gas emissions are consistent with magma (molten rock) being within the volcano’s chambers.

However, to confound matters, the increased level of volcanic tremor reported in May has now declined to typical background levels.

In an Alert Bulletin issued late Tuesday afternoon, Brad Scott, the Volcano Surveillance Co-ordinator for GNS Science, reported, “These observations remain consistent with the volcano-hydrothermal system responding to recent eruptions and ongoing interaction with magma in the volcano conduit. The volcano remains in a state of unrest and the possibility of further activity remains at the volcano. If further eruptions occur, they may occur without warning.”

The Alert Level of Mt. Ruapehu remains at 1 (signs of unrest).

[Compiled from data provided by the GeoNet project and its sponsors EQC, GNS Science and FRST.]

7 Responses to “Unrest Continues at Mt. Ruapehu”

  1. bruce says:

    Firstly, thanks for the heads-up on the geonet volcano monitoring site. Totally love the RSAM and SRAM page.. but not knowing who to ask thought I may as well start here..

    If you look at the low frequency signal (1 Hz and below) there’s a definite tie-up between Ruapehu, Taupo and even through to Okataina and White Island, with the signal peaking on May 8, 18 and 22 on all charts..

    Is there any explanation for this that you know of?

  2. Ken says:

    Your question needs the skills of someone who knows the ins and outs of the RSAM and SSAM plots.

    I’ve found that the GeoNet people are keen to help with queries, so you might like to drop them an email. If they can’t answer the question, I’m sure they’ll flick it onto one of the volcanologists.

    Let us know if you find anything out.

  3. bruce says:

    Cheers Ken,

    done. Let’s see if they reply.

  4. bruce says:

    Hi Ken, here’s the response I got from geonet:

    The very low frequency signal that you see is called “microseism” ….
    this is a very low freq signal usually produced by the weather, in
    particular strong winds and large seas, the surf crashing on the west
    coast and the wind shaking forests, buildings etc. As the weather systems
    are large and lie across many areas at the same time you will see the same
    signal in many places at once. It is usually more common on sites exposed
    to the west (eg Taranaki).

    I’m stoked they took the trouble to reply!

  5. Ken says:

    Thanks for sharing that response, Bruce.

    I have found that GeoNet and GNS Science staff are usually happy to answer questions and share what they know. The co-operative spirit extends through both the scientific and support staff and has been there since the days when the DSIR ran the Seismological Observatory.

    Their short courses and seminars are worth considering too, if you happen to be visiting one of the venues at the right time. The tour of the Wellington Fault that a group of us did with a couple of “tame” seismologists a few years ago was both informative and entertaining. A most memorable experience.

  6. bruce says:

    That’s going to be tricky. I now live in Germany!!

  7. Ken says:

    Yes, I noticed that. 😀
    There’s always the chance that you’ll be back when one of the seminars is running, but I couldn’t resist adding a plug for their excellent courses and seminars anyway. 😉

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