Eruptions Newsletter #4 for April 4, 2025

Lately it seems like all the volcano news is about lava flows and that won’t change in this week’s newsletter. I realize I mentioned that I would start with a subscription model in April, but that will not happen just yet. So, you all get to enjoy the newsletter in its entirety for the time being.

Activity News

Sundhnúkur, Iceland

It has been a while, but the eruptions near Grindavík in Iceland resumed this week. This week’s resumption on April 1 of activity started directly adjacent to the protection barrier built on the north side of the village and ended up breaching the barrier. At the time, there was concern that this eruption could endanger Grindavík more dramatically than previous eruptions. Thankfully, the eruption was relatively short lived. Maps of lava flows released by the Icelandic Meteorological Office (IMO) show a small set of fissures just south of the barrier, but the lava itself did not reach any buildings.

Much like previous eruptions, the IMO was able to forecast the start of the event looking at the seismic, GPS and borehole data from the area. Deformation of the crust due to magma rising will change all three of these parameters in the form of more earthquakes, motion of the land surface and increase in stress in the crust respectively. The focus of the unrest was much closer to Grindavík than what occurred in the last eruptions in November 2024, so evacuations of the village and the nearby Blue Lagoon were called.

The new fissure reached over 1,200 meters from end to end, with lava flows and small lava fountains issuing from the crack. However, the eruption was brief, ending by later on April 1.

One interesting note: the IMO reported that they think between 15-22 million cubic meters of basalt magma had intruded under the area since the November 2024 activity. This new eruption did not erupt anywhere close to that volume. On top of this, the dike of intruded basalt, based on seismic data (see below) was likely 20 kilometers long. So, although all the current indications suggest that another eruption isn’t likely soon, there is a lot of magma that was intruded from depth.

Now, I’m not one for sibling rivalry, but my sister and her family had just arrived in Iceland for a vacation the previous day. You can imagine some of my thoughts when I read that eruptions had begun anew.

Kīlauea, Hawai’i

On March 31, another eruptive episode started at Kīlauea. This sixteenth salvo produced 600-700 foot tall lava fountains for nearly 24 hours (see below), making it one of the most vigorous eruptive episodes so far. The entire episode lasted over 36 hours and covered half the floor of Halema’uma’u Crater with another layer of lava flows.

This seems to be the current pattern at Kīlauea, where episodes of vigorous lava fountain and flows are punctuated by quiet as the system “recharges”. Likely this is due to magma rising into the upper parts of the volcano from the source of the magma in the upper mantle below Hawai’i. So, it is very hard to say for just how long this activity will persist.

Poás, Costa Rica

A few weeks back I mentioned that Poás in Costa Rica has started erupting again. OVSICORI is reporting that the unrest is becoming more intense, with a series of small explosions from the volcano over the past week. Some of these blasts sent ash up 1,000 meters (3,200 feet). On April 1, incandescent blocks were thrown up to 400 meters (1,300 feet) above the active vents. The increasing activity prompted the Alert Status at Poás to be raised to orange (or the 3rd highest of 4).

The combination of earthquakes, small phreatomagmatic explosions (I’ll get to that momentarily) and inflation recorded at the volcano all suggest that more activity is coming. Now, Poás does have small lakes at the summit, so new magma intruding the upper parts of the volcano interact with lake and groundwater, leading to steam-and-magma driven blasts — yes, the phreatomagmatic explosions.

Odds & Ends

Nothing much to add here this week. Trust me, I looked!

Sounds of the Week

Iceland has produced a lot of volcanologists over the year, including Haruldur Sigurdsson who wrote the great book Melting the Earth. However, there is likely no Icelander more famous that Björk. So, this week’s sounds are my top songs by Iceland’s favorite former child star turned pop star turned genius weirdo.

Here’s the thing with Björk: she knows who to work with. “Bachelorette” was directed by Michel Gondry and it is the ultimate trippy story within a story video. It is also one of my favorite Björk songs from my favorite Björk album, Homogenic.

Speaking of great collaborations, “All Is Full of Love” was filmed by Chris Cunningham. He made some of the best and weirdest videos of the 1990s including ones by Aphex Twin, Nine Inch Nails, Jesus Jones and Portishead. If you are someone who likes to dig deep into discographies, I’d recommend the Plaid Remix of “All is Full of Love”.

I am less familiar with Andrew Thomas Huang, but Björk’s “Mutual Core” is a must for people in the intersection of “geology fans” and “weird Icelandic singer fans”. You may never see cross sections the same way again.

So, it turns out that Lars Von Trier was a terrible person to Björk when she filmed Dancer in the Dark with her. It doesn’t diminish the fact that “I’ve Seen It All” is a triumphant song, especially the version with Thom Yorke from Radiohead.

Even before Björk became Björk, she was in the Sugarcubes. Now, I was just becoming aware of music when the Sugarcubes were at their most popular. I really tried to get into them because they seemed cool. However, the only song I really liked was the appropriately named “Hit”. I do feel bad for Einar Örn Benediktsson, the guy who throws the weird “rap” verse, because it is, well, super weird. Turns out he was briefly politician in Iceland who was part of the Reykjavík city council for 4 years.

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