Eruptions Newsletter #15 for June 20, 2025

Programming note: there won’t be a new newsletter or podcast next week. Look for the next ones of each during the week of June 30.

Activity News

A mere two weeks ago over on my podcast 5 Minute Volcano I took a look at Lewotolok in Indonesia. In that episode, I mentioned that Lewotolok is very close to the similarly named Lewotobi on nearby Flores Island. Well, it turns out that Lewotobi had something brewing and erupted with force on Tuesday.

Lewotobi (also known as Lewotobi Laki-laki) has been having low-level eruptions since December 2023. The volcanic edifice is actually two overlapping volcanoes, Lewotobi Laki-laki and Lewotobi Perempuan — literally Lewotobi Husband and Wife (or Man and Woman). The current activity is focused the former.

Although the eruptions have been fairly mild as explosive eruptions go, they have also been deadly. An eruption in November 2024 piled ash up on nearby villages leading to the death of 10 people. That blast sent ash and volcanic debris 2 kilometers (~6,500 feet) over the volcano.

The latest eruption on June 17 sent ash and volcanic gases much higher, topping out at - depending on your source - over 5 kilometers (~16,000 feet) or 11 kilometers (~35,000 feet). Why the difference? It likely comes down to how the sources are measuring the maximum height and/or if the ash has continued to drift upwards, making it a hazard for aircraft up to 35,000 feet.

Luckily, no casualties have been reported so far for this transient blast from Lewotobi. Indonesian authorities have placed the volcano on its highest alert status. However, the ash in the air did prompt flight cancellations in and out of Bali. Indonesia authorities still have a 7-kilometer exclusion zone around the volcano as well.

One side note: in the New York Times coverage of this eruption, I saw this brief description:

Ok, so, no. There was no “smoke” or “flames”. Neither are produced during a volcanic eruption. The “smoke” is a mix of volcanic gasses like water vapor and sulfur dioxide with volcanic ash (which is not formed from burning but is shards of volcanic glass). In the linked video, the “flames” look more like volcanic ash being hit by evening sunlight.

Iliamna, Alaska

So, this isn’t an eruption update as much as a monitoring update. Over the past week, a number of seismic events (earthquakes) were recorded on the one functioning seismic station on Alaska’s Iliamna. Now, one seismic station does not a network make, so right now the Alaska Volcano Observatory has an “unassigned” status to the volcano. This doesn’t mean that there is no monitoring, but rather they can’t be sure of Iliamna’s status at the moment.

The earthquakes recorded at Iliamna could be cause for concern, except that the interpretation of the seismic signal from the lone seismometer is not magmatic/volcanic. Instead, they appeared to be rock or ice falls, which is not uncommon during warmer summer weather in these Alaskan volcanoes. This is doubly so when considering that a relatively small deep tectonic earthquake (M4.2) occurred at Iliamna last week.

Kīlauea, Hawai’i

And wouldn’t you know it, just as I was about to put this newsletter to bed, the 26th eruptive episode began. As with most of the episodes this year, we have impressive lava fountaining reaching ~1,000 feet (300 metrers) and lava flows (see above). You can watch all the action on the livestream:

Volcano Word of the Week

The Volcano Word of the Week is fumarole. This is a term used to describe places on volcanoes where gases escape. Most of these volcanic gases are water vapor, sulfur dioxide, hydrogen sulfide, carbon dioxide and other compounds like hydrogen chlorine and hydrogen fluorine that occur in gas form.

These vents can vary in temperature from 100°C to 1000°C depending on the source of the heat — ultimately, the magma intruding the crust under the volcano. The magma doesn’t need to be near the surface as the fluids circulating above a magma body can recirculate heat quite efficiently. So, the magma might be many kilometers down, but the hydrothermal system (heated water, more or less) can keep things toasty.

Volcanoes that haven’t had eruptions for decades, centuries or millennia can have vigorous fumaroles. Yellowstone is a great example, but many volcanoes have weak-to-strong fumaroles. I remember seeing the persistent fumarole on Ollagüe in Bolivia/Chile in the cool morning air when I was working in the Andes, but it likely hasn’t erupted in over 10,000 years.

Lots of different kinds of minerals can form near fumaroles such as native sulfur, sulfides like pyrite and even valuable minerals like opal. Some places even actively like the sulfur being produced, most famously at Kawah Ijen in Indonesia. There are some cool places like Alaska’s Valley of 10,000 Smokes where you can even see fossil fumaroles where the remnants of all the alteration from fluids and heat are preserved.

However, fumaroles and fumarole fields are hazardous places. The sulfur, chlorine, fluorine and other acid compounds can be very bad for your lungs, eyes, mouth, nose, and throat when you breathe in the vapors. You can notice this at places like Bumpass Hell near Lassen Peak where the boardwalk takes you through some fumaroles. Catch the wind the wrong way and you get a blast of vapor leaving you with a mild burning sensation. This is why it is always wise to either keep your distance or have a gas mask. Getting too close and inhaling too much can be fatal.

Odds & Ends

This year was the 45 anniversary of the catastrophic eruption of Mount St. Helens in Washington. We’re almost half a century since the blast! Yet, the copious volcanic debris from that eruption still impacts all the local streams, rivers, and other water bodies around the volcano. This article gets into the details of what the US Forest Service has to do to keep all that volcanic sediment from continuing to cause trouble near St. Helens.

Don’t do dumb things. So, I was a NPS Ranger for a summer and if there is anything I learned, it was that people make remarkably poor choices. Consider this very lucky fellow near Kīlauea who fell off a cliff … on an erupting volcano … at night … and lived to tell the tale. Folks, stay on the trails, read the signs about dangers and, as I’ve mentioned before, think “would my mother/friend/wife/husband/cat be happy I was doing this?” No view or photo is worth your health or life.

Sounds of the Week

People spend a lot of time these days trying to name a “Song of the Summer”. That’s silly! No one song can define a summer for even 1% of the population. Anyway, I hope you have a song that maybe is the soundtrack of the first part of the meteorologic summer (in the northern hemisphere … mid-latitudes). Remember, the actual solstice is today, so astronomically, summer just started!

All that to say, these are a few good summer songs from this year:

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

Be sure to check out my podcast, 5 Minute Volcano and the Patreon page for the Eruptions Newsletter/5 Minute Volcano Podcast.