Eruptions Newsletter #1 for March 3, 2025

It has been a few years, right? Eruptions (as a blog/column) went away in 2017, but times, they change. I decided it was time to dust off the old name and relaunch as a newsletter that will be all about (well, mostly about) volcanoes. I am not going to cover all the activity everywhere, but instead highlight cool/interesting/important stuff, offer my insights as a volcanologist and Earth scientist and generally try to inform and amuse.

Rather than continue this preamble, why not just dive into the first newsletter.

Activity News

Much of the attention across early 2025 have been focussed on three places: Santorini, where nothing has happened; Kīlauea, where many things have happened and Etna, where, well, many things have also happened. I covered some of the background to the unrest at Santorini in my preview newsletter, so you can check that out. If you want all the gory details of unrest on the planet, remember to read the Smithsonian/USGS Weekly Volcanic Activity Report.

Kīlauea, Hawai’i (USA)

Hawai’i’s most active volcano is being just that: active. Earlier this week Kīlauea experienced is 11th “episode” (in other words, eruption) of the current activity that started in late 2024. Much of the floor of the Halema’uma’u Crater has been paved with new lava since then. Most of the eruptions are coming from vents on the southwestern corner of the caldera generating a mix of impressive lava fountains (see below) that reached over 100 meters in height and lava flows.

Episode 11 produced 13 hours of intense lava fountaining from this new cone that has formed inside Halema’uma’u. The USGS report on this episode has some great pictures of the volcanic scoria and debris being produced by all this fountaining of basaltic lava. If you want to see this kind of activity in action, check out the video from Episode 10 earlier in February where you can hear the low, jet engine-like roar of the eruption (as well as the wind).

We haven’t had an update of the map for the lava flows since February 7 (I wonder why … see below), but there aren’t many signs in the earthquakes, degassing and deformation that would suggest that we aren’t going to continue to see eruptions off and on in the foreseeable future. If you want up-to-the-moment news, HVO has a “Volcano Messages” feed that offers little blurbs as the activity changes.

Etna, Italy

Not to be outdone, Etna returned to vigorous activity in 2025. The current report from the INGV Etna Observatory is: (1) effusive activity from an eruptive fissure at the base of the Bocca Nuova crater; (2) strombolian activity at the South-East Crater and; (3) degassing at the Bocca Nuova Crater, Voragine and North-East Crater. That’s a lot of action!

What does it mean? Well, the first is lava flows from a fissure that is active at the base of the main Bocca Nuova crater on the volcano. That is what we can see in the satellite images snaking down the southwestern slopes from over 3,100 meters down to less than 1,800 meters. That means the flow is over 4 kilometers now! The thermal images captured by Sentinel-2 (below) really make the lava flows stand out.

The second, “Strombolian activity”, means that the South-East crater is host to regular, small explosive eruptions caused by large bubbles moving up through lava/magma conduit and “popping”. That “pop” is the explosive eruption that sends lava bombs and ash tens to hundreds of meters from the vent. Sometimes small lava flows can form as well. This kind of activity is very common at Etna (and its namesake neighbor, Stromboli).

Finally, the third bit of activity, degassing, just means that volatiles (mainly water, carbon dioxide and sulfur dioxide) are diffusing to the surface through these craters. This betrays the presence of new magma rising underneath the volcano and losing its gas content as it rises.

The INGV posted this cool 3D map (above) of volcanic tremor at Etna and it shows the path the magma takes from beneath the volcano to the eruption sites. Most strikingly, it isn’t straight up but rather at an angle. Again, this isn’t uncommon as the magma is likely taking the “path of least resistance” like a weakness in the volcano or a fault.

Atka, Alaska (USA)

The very small explosion at Atka isn’t going to be news almost anywhere but in this newsletter, but having a soft spot for Aleutian volcanoes, here we go! Atka is actually a complex of volcanoes out in the island portion of the Aleutian arc. Up until March of last year, it has been quiet since 2006. However, in March 2024, a small explosion occurred in the Korovin crater … and then nothing else. Fast forward to February 20 of 2025 and another small explosion came from the same area of the summit lake in the Korovin crater.

Why is this interesting? It is a good example of “what the heck is going on here?” On one hand, small blasts like this could be a harbinger of something more dramatic. The Atka Volcanic Complex does have multiple confirmed VEI 2-3 eruptions over the past few hundred years. However, blasts like this could also just be steam-driven events related to heat in the hydrothermal system. Without being able to sample the ash produced, it can be hard to tell, especially at volcanoes without much/any realtime monitoring.

For now, the Alaska Volcano Observatory notes that “Additional explosions are possible in the near future, but unlikely”, which makes you think that they are leaning towards this being a small, one-off steam-driven event. However, even little events like the February 20 pop are always worth a quick look.

Volcano Research

Zircon at Mt. Hood

Klemetti, EW and others, 2025. Young zircon ages and compositions at Oregon’s Mount Hood as evidence of high-silica magma storage underneath an andesitic arc volcano. Geosphere (open access).

I might be a little biased here, but this paper is great.

Ok, that’s a joke because I am the first author, but this is a product of many years of work by me and multiple research students, as well as collaborators across the country. The key takeaway from the study is that the magma stored underneath Mt. Hood in Oregon is more complicated than what the lava erupting from the volcano might suggest. In fact, the presence of zircon that are likely less than a few thousand years old all point to some high silica (rhyolite) magma cooling underneath the volcano.

Now, this project was not one I had originally planned on doing. I was asked by Adam Kent (Oregon State) and his then-Ph.D. student Alison Koleszar (now at Colgate) to take a whack at trying to get zircon out of Old Maid lavas from Mt. Hood. These lavas likely erupted only a few hundred years ago, so they can definitely help us understand how a potentially active volcano like Mt. Hood behaves.

Anyway, we were able to get zircon out of these and other recent lavas from Mt. Hood and we took them to the ion microprobe lab at Stanford. This instrument allows you to collect data on the isotopic composition of uranium, thorium, lead and more in individual crystals. With the potential for them to be so young, we used uranium-thorium disequilibrium dating on these crystals. We expected they would likely be tens to hundreds of thousands of years old, similar to what I had found at another Cascade volcano, Lassen Peak as well as what other researchers had found at Mount St. Helens.

Turns out that we were wrong! Sort of! Many of the zircon were so young that their age was more-or-less within our ability to resolve them from the date of the eruption. That’s super young for volcanic zircon, likely only hundreds to thousands of years old. There were some older ones, but unlike the two Cascade volcanoes mentioned above, they were relatively rare.

Now, Mt. Hood has pretty much only erupted andesite, but zircon is not likely to grow in andesite. Instead, it wants to grow in magma with more silicon in it that is also cooler. So, all these young zircon must be growing in some rhyolite magma that is part of the Mt. Hood magmatic system that never erupts as rhyolite. Instead, the stuff erupting at Mt. Hood represents a mix of multiple types of magma to make something in-between.

This is the model that Adam Kent had proposed for Mt. Hood, but the first hard evidence that the high-silica magma is (a) down there and (b) down there now and in the recent past. In fact, the behavior at Hood is similar to other volcanoes around the world, so maybe we’ve gotten a better grasp at the magmatic systems at Hood-type volcanoes.

Odds & Ends

Science in the States

You might have heard there have been some changes in the US government. I would say that the changes are unequivocally bad for science and education in this country. Science is still moving forward whether various political parties want it to or not. However, the massive cuts and spending freezes in the National Science Foundation as well as layoffs at the US Geological Survey and NASA means that we are (intentionally) making the country less prepared for future geologic disasters.

Now, I realize that humans are really bad at thinking long term. This is quadruply so for business types who only think about the profits of a single quarter — and they are the people in power right now. The return-on-investment for primary science is incredibly high when you consider innovation and losses prevented by better hazard mitigation. It is just that sometimes that ROI isn’t seen immediately … or in a year … or decade.

I might be overly optimistic that the US can bounce back from this anti-science regime in power right now. There are going to be many, many people who would have been excellent scientists and researchers (and educators!) that now won’t get that chance. This will hurt and the US will no longer be the world leader in scientific knowledge and innovation. However, I do hope that maybe this opens a lot of eyes of the excellent work that the government does for understanding our planet — and that “highly productive” work is more than just making the most money.

Vesuvius

Ars Technica ran an article on Friday about a new study on a victim of the 79 CE eruption of Vesuvius. A lucky(?) resident of Pompeii had their brain converted to glass after being engulfed by the seeringly hot pyroclastic flows. This could have fallen under volcano research, but I’m putting it here mostly for Jennifer Ouellette’s fabulous subheadline: “Fresh analysis with calorimetry, X-rays, electron microscopy lend support to hotly debated theory.” {chef’s kiss}

Sounds of the Week

When you subscribe to a newsletter written by me, you are also signing up for me talking to you about music. You can feel free to gloss over this section, but you would try out some of these songs. I thought I’d start by Top 5 sounds of the week with an appropriate thematic one — my top 5 songs about volcanoes.

Top 5 Songs about Volcanoes

5. Magma by Gojira - You might not like French metal as much as I do.

4. Volcano by Presidents of the United States of America - Points for an absolutely dumb video.

3. Volcanoes by Islands - Global winters! Calderas! Alaska!

2. Lava by the B-52s - So many volcanoes name dropped.

1. Cities in Dust by Siouxsie & the Banshees - I have to admit that I didn’t realize this was about the 79 CE eruption of Vesuvius and resultant burial of Pompeii … like for a decades. Sometimes I’m pretty dumb.

Questions? Comments? Thoughts? Feel free to send me a note or follow me on Bluesky (@erikklemetti.bsky.social).