GeoNet volcanic activity bulletins.
Update, April 6, 2023, 10:44 a.m., Pacific: Per GeoNet this week:
The number of earthquakes at Taupō Volcano over the last few weeks has decreased and almost returned to what is normally seen. Meanwhile, uplift of the floor of the central part of Lake Taupō continues. The volcanic alert level remains at 1.
March 7, 2023, 8:27 a.m., Pacific: GeoNet did issue an update, and there is also a good article on the situation — which is unchanged — from the New Zealand Herald (and probably from many other sources that I haven’t read).
Per GeoNet (their emphasis):
On Sunday 5 March 2023, GeoNet recorded an M4.4 earthquake beneath Lake Taupō. The earthquake rupture occurred within 10 km of the surface and shaking was felt mostly along the lake shore. So far, more than 20 aftershocks have been located.
The number of earthquakes per week has been declining since November, but we have seen a slight increase prior to Sunday’s quake…
We also noticed a small signal on our newly installed tsunami sensors in the lake at the time of the earthquake, but more analysis is required to find out its cause.
The recent number and size of earthquakes, including the M4.4 event, is within our expectations for a volcano at minor volcanic unrest. This is confirmed by our other observations to date which show continuous activity, but no significant changes compared to the previous months of unrest. We also did not notice any changes in volcano monitoring indicators following the M4.4 earthquake.
Therefore, the Volcanic Alert Level remains at 1 at Taupō volcano, and the Aviation Colour Code at green.
The Herald has interviewed volcanologists. Per the article linked above:
“The recent unrest is very likely driven by magma movements and the related movement of fluids, and they can trigger earthquakes – but [they] can also be triggered by long-term plate motion in this area,” GeoNet duty volcanologist Dr Yannik Behr said.
“So, it’s difficult to attribute one particular cause for an earthquake, but we think it’s probably related [to the unrest].”
Although there’d been a noticeable decline in earthquake activity since November – with between 10 and 50 recorded each week – Sunday’s event was preceded by a slight uptick.
“We also noticed a small signal on our newly installed tsunami sensors in the lake at the time of the earthquake, but more analysis is required to find out its cause.”
Overall, Behr said the number and size of observed quakes was within expectations for a volcano at “minor” volcanic unrest.
“This is confirmed by our other observations to date which show continuous activity, but no significant changes compared to the previous months of unrest.”
As for how long the episode was likely to drag on, scientists couldn’t say.
Earlier this year, GNS Science volcanologist Brad Scott said the average duration of larger bouts on unrest over the last 150 years was about eight months – and he gave a 50-50 probability of it becoming a lengthier-than-normal period.
“In the past, we’ve seen unrest episodes that have lasted much longer than this,” Behr said, noting one that unfolded over three years in the late 1990s.
“So, these can last for quite some time.”
Nonetheless, the chances of the episode turning into something much more significant were small, and of 17 such periods over 150 years, none ended with a big eruption.
“We can’t exclude the possibility of one, but we don’t see any signs of an imminent eruption,” Behr said.
“For example, one thing that we look for certain types of seismic activity that shows really shallow magmatic or volcanic fluids, and we don’t see that at the moment.”
Over its 300,000-year eruptive history, Taupō – regarded as the world’s most frequently active super-volcano system – has unleashed some of the biggest blows ever documented.
They include the gigantic Oruanui eruption around 25,400 years ago – in which more than 1100 cubic kilometres of pumice and ash was spewed into the planet’s atmosphere, and as far afield as Antarctica.
Taupō’s most recent major episode, some 1800 years ago, fired out more than 120 cubic km of pumice and ash and obliterated the surrounding landscape, while widening the basin that Lake Taupō mostly fills today.
In any given year, however, the statistical probability of something like that occurring remained slim.
One 2020 modelling study put the annual probability of a Taupo eruption at any size at a very low chance of one in 800 – or at between 0.5 and 1.3 per cent – within the next 500 years.
In this one layperson’s opinion, we’ve come a long way in communicating volcanic hazard over the last twenty-some years.
Back twenty-some years ago, when the news first filtered into public consciousness that Yellowstone was a supervolcano, things got sensational at times.
There was such a gap between Science and Us about this news.
Now we’re all talking about it rationally, and that’s Grrrrreat!
Speaking of Tony the Tiger, what if Yellowstone had developed a supereruption back in the “Yogi Bear” days, when it was “just” a park to everyone (which it still is, of course)?
Fiction is really hard, so I’ll just put the idea out there, if anyone wants to have a go at it.
I’d approach it through the scientific paradigm of the 1960s (plate tectonics) — which had Science in an uproar and which doesn’t provide a “simple” reason for Yellowstone, which is not a subduction zone volcano — and the societal Sixties revolution, which had everyone reeling.
What if we all had had to depend on each other to survive something so intense and unexpected and mysterious, instead of fragmenting into cliques as we did, holding one particular facet or other of Rightness (and sometimes Self-Righteousness and/or Despair) and hating anyone we chose to think of as “wrong”?
And let’s not forget the Cold War. That crazy idea allegedly suggested by that one Russian aside, what if Jellystone had launched its supertantrum early in or just before the Cuban missile crisis?
Distant earthquakes, local earthquakes, and nuclear blasts would be devastating events but would not trigger Yellowstone to erupt. YVO’s scientist-in-charge Mike Poland describes why in this monthly video update for March 1, 2023. pic.twitter.com/qKCOTFAajw
— USGS Volcanoes🌋 (@USGSVolcanoes) March 2, 2023
Quite a good novel could come out of it, but it would have to be written by someone who lived through those times — the actual way it was has not come down intact to our descendants over these past roughly sixty years.
March 5, 2023, 1:45 p.m., Pacific: There has been no update or change in status from GeoNet, but I just saw this, tweeted about 16 hours:
This afternoon's M4.4 within the Taupō volcano caldera is the 3rd largest quake in the ongoing sequence which is now around 1,700 earthquakes since May 2022. The cluster of main M4.0+ quakes have been around the Horomatangi Reef. Summary of todays M4.4 @ https://t.co/hG17S48OH2 pic.twitter.com/HiI5eEgJXh
— Hauraki Gulf Weather (@GulfHauraki) March 5, 2023
No cause for alarm — just a sign that whatever is going on down there is continuing.
I’ll pin this again, in case GeoNet issues a statement.
January 12, 2023, 4:05 p.m., Pacific: No changes, but GeoNet did publish an update today with lots of interesting information.
Will pin this again for a while since there’s not much else going on and it isn’t every day that we have a supervolcano under alert (though NOT for an impending supereruption!).
October 12, 2022, 1:24 p.m., Pacific: No change, but read the full October 11th update.
October 6, 2022, 6:37 p.m., Pacific: No new updates — this is just to let you know that the experts have published a FAQ on Taupo’s unrest.
It’s interesting and detailed. Among other things, it answered my curiosity about what the Taupo Volcanic Zone is and whether all those volcanoes in it are connected (they’re not).
September 30, 2022, 10:48 a.m., Pacific: Volcanologists report no major changes in their latest bulletin, and the low-level unrest and alert continue.
September 21, 2022, 4:12 p.m., Pacific: There are no new official updates — GNS Science doesn’t routinely post daily updates like the USGS often does when volcanoes are restive.
I just wanted to point you toward this article by volcanologist/blogger Erik Klemetti.
He covers this far better than I could, of course, so there’s no need for me to do that special Taupo post this coming Sunday after all (the regular Sunday Morning Volcano feature is about a supervolcano, but it’s in California, not New Zealand).
Taupo, in New Zealand, is a supervolcano, but such volcanoes have “normal” eruptions, too.
It’s also a restless caldera, which means that it has earthquake swarms off and on. It’s having one now, and because of this, the volcanologists decided to raise the alert to the lowest stage, level 1.
No supereruption is pending — Taupo is heavily monitored and the precursors of such a thing likely would be HUGE — but maybe we’ll get to see a “normal” one, somewhere in the caldera?
If so, it will be Surtseyian (explosive) because of the crater lake.
This is not an emergency, and my schedule is tight this week, so I’m going to let the volcanologists speak —
— and plan to do an in-depth post this coming Sunday, unless something dramatic — and most probably nonsupersized — happens before then.
Featured image: NASA via Wikimedia, public domain.