Think volcanic eruptions, and likely Mount Vesuvius or Mount St. Helens comes to mind. But there’s another eruption in the annals of volcanic history worth knowing about: the 1783 shuddering to explosive life of Iceland’s Laki, which may mark, says journalist Alexandra Witze, one of the first instances of a global consciousness.
In their new book Island on Fire, Witze and co-author Jeff Kanipe trace the story of this eruption through modern scientific understanding and detailed historical records. We recently got a chance to speak with Witze about the book.
(Note: This interview has been lightly edited for clarity and length.)
World Science Festival: What made you want to focus on Laki as opposed to another famous volcanic eruption, like, say, Vesuvius?
Alexandra Witze: I actually got into Laki in 2010. I went to Iceland for the first time that summer to do some reporting on the—you know, the really long-named volcano that starts with an E?
WSF: Oh! That one—Ey-yah-fee-yokel, right?
Witze: Pretty close! Eyjafjallajökull—which I spent a lot of time pronouncing, actually.
I was reporting for Science news about why ice-covered volcanoes are so dangerous. When I was there, I was driving around with some University of Iceland grad students who were out servicing instruments to monitor several different volcanoes. At the end of a long day, one waved over his shoulder and said, ‘Over there are the flows from the Laki eruption, which you’ve probably never heard about but which was way worse than what we just went through [with Eyjafjallajökull].’ That made me sit up in my seat.
WSF: You tell a lot of the story of Laki through the eyes of a Lutheran priest named Jon Steingrimsson. How did you come across him?
Witze: As soon as we started reading about Laki, we heard about this guy Jon. The chronicle he wrote about the eruption was incredible in its scientific detail. He was a reverend, but he was really interested in the natural world, and he wrote down, day by day, everything that was happening. It really tells us about what happened during this incredible eruption—where the lava went, where the ash went.
WSF: What is Laki’s current status?
Witze: It hasn’t erupted since 1783. And nobody has any record that it erupted before 1783. Basically it had one incredible, one-off eruption and then there’s been no activity.
WSF: Laki is different from what we normally think of as a volcano, right?
Witze: Yeah. It’s not a big fancy peak with stuff going out of the top like Mount Fuji or Mount St. Helens. It’s a long chain of craters along the landscape. It almost looks like a bunch of meteorites came down and smashed one after the other. What happened during the eruption is the ground ripped apart along this very long line, and what’s been described as “fountains of fire” started to shoot up. You didn’t have ash blowing out of a single cone, you had sheets of fire coming out of this big rent in the ground.
WSF: Are there misconceptions people have about volcanoes—maybe from movies?
Witze: Everyone wants to talk about Pierce Brosnan in Dante’s Peak. But I think, mainly, most people don’t have a good conception of where most of our volcanoes are and which ones are dangerous. For instance, Indonesia has the most volcanoes in the world. And in the U.S., people might think there hasn’t really been an eruption since Mount St. Helens. But Alaska has a lot of active volcanoes—they throw up a lot of ash and interfere with the plane flights coming over the Pacific.
WSF: It seems like we might under-appreciate the huge ripple effects that occur from volcanic eruptions.
Witze: That was the really interesting thing to us about the Laki eruption. The gases from Laki, which were really rich in sulfur, got picked up by the wind and carried all the way to England and Germany. Natural scientists across Europe were trying to figure out what was going on. There was strange weather, weird fog, things smelled kind of bad, trees were withering up and dying…I really think that Laki was the beginning of the dawning of this global consciousness—that something way around the world could affect you.
WSF: Are we getting any better at predicting when volcanoes are going to erupt?
Witze: Yes and no. The yes part is there are some volcanoes that are really well monitored. If you have enough instruments around a volcano, you have a pretty good idea if and when it’s gonna erupt. In the U.S., particularly the Cascade volcanoes, and in Iceland, we have a good sense of it. The parts we don’t know about are the volcanoes where there aren’t a lot of instruments because maybe they haven’t erupted in a really long time. Like in 2008, there was a Chilean volcano called Chaiten that erupted, and nobody had any idea it was close to going off.
WSF: Which volcanoes do volcanologists tend to be leery of? What’s likely to go off next?
Witze: If you talk to volcanologists, they talk a lot about Indonesia because there are a lot of volcanoes there that we think are dormant but maybe they just aren’t. But it’s the one you’re not watching that’s gonna get you.
Excerpt From Island on Fire:
In the following excerpt, Witze reveals the science underlying the creation of the molten rock that surges from a volcanic eruption:
“Heat has been lurking in the planet’s interior ever since it formed 4.5 billion years ago, when Earth coalesced from a disc of gas and dust swirling around the newborn sun. Much of the planet’s internal heat comes from radioactive elements left over from its fiery birth. Such elements include thorium, uranium and potassium, which can take billions of years to decay into less radioactive substances. The nuclear breakdown releases heat that percolates up toward the surface.
Chemistry comes into play in determining which particular rocks are destined to melt. Most rocks are made of minerals in which atoms of elements such as silicon and oxygen are arranged in regularly repeating, or crystalline, patterns. Other elements, such as iron or magnesium, tuck themselves into this arrangement. Depending on what atoms are in the structure and how tightly they bond to one another, the atoms can be snuggled close together or strung out more loosely, like pearls on a string. When temperatures rise, the first chemical bonds to break are those between atoms that are less tightly linked; thus different minerals have different melting points, depending on how their chemistry is arranged. A rock made up of different minerals will melt its mineral types one by one rather than all at once. Over time, the chemistry of the rock changes as part of it melts out while the rest remains solid.
Finally, pressure is the key that links heat and chemistry together to produce molten rock. If you take a chunk of surface rock and raise its temperature to the melting point, it melts, naturally. But put that same chunk hundreds of kilometres deep in the mantle, and the high pressures will keep it solid. That’s why most of the Earth’s mantle is solid. It’s hot, to be sure, but the pressure is high enough in most places to keep the rocks from melting completely.”
Excerpt from Island on Fire by Alexandra Witze and Jeff Kanipe. Published by Pegasus Books. Reprinted with permission.