Last week I watched Earthstorm Volcano, the second episode of the series. I was expecting a nice documentary starring Fagradalsfjall, the 2021 eruption in Iceland, and instead I got some high-octane nightmare fuel. It did indeed feature Fagradalsfjall and then it built up and up and up to bigger and more destructive volcanoes and finished on one right here in Europe that I’d never heard of, Campi Flegrei.
I’m not really the documentary type but it crossed my Twitter timeline because someone I follow was interviewed for it and I’ll make an exception for documentaries about Iceland or about volcanoes or especially about Icelandic volcanoes. It’s a four-part series and I haven’t bothered watching Tornado, Earthquake or Hurricane. I’m a volcano girl. I’m now a girl who has nightmares about volcanoes.
So, yes, it starts off at Fagradalsfjall which measures a 1 on the Volcanic Explosivity Index, or VEI. That’s because it’s not explosive. It’s effusive. Essentially, the magma chamber underneath just overflowed and thin lava poured down the valley. Thin lava like this is just as destructive as thicker lava but thanks to Iceland being largely uninhabited – in that 80% of people live in the capital area which leaves about 20% to gather in small bunches around the coast – there wasn’t really anything around to be destroyed. The land was owned by farmers who used it for grazing sheep and I imagine they’ve earned ten times what they would have in the rest of their lifetime through parking fees so they’re probably not too unhappy at the loss of their grazing land.
I didn’t see Fagradalsfjall – in 2021, Iceland still had either entry requirements or random testing and even for a volcano, I can’t have a swab put down my throat. But I saw Meradalir this summer, which was a smaller version a little deeper into the mountains. It’s all very touristy – there’s a handy mountainside to sit on overlooking the eruption which fountains away in its crater and pours out a river of red and black lava and some gas but there’s no real danger even a couple of hundred metres away. There were hundreds – thousands – of people the day I was there, which was more than two weeks in when the eruption was starting to quieten down. I can only imagine how many people were there in the early days and I’ve seen the photos of the traffic jams at the 2021 eruption, when this was a novelty, an accessible eruption not seen here for 800 years. In fact, Earthstorm says 350,000 people visited Fagradalsfjall, which isn’t bad for a country with a population of around 360,000. It was a lovely eruption. the sort that can make you fond of volcanoes.
Then we step up a gear. Earthstorm took us to Cumbre Vieja in the Canary Islands – or technically, a side vent which created a newborn volcano of its own yet to be named. This one was a 3 on the VEI. It was more explosive than Fagradalsfjall but it was also pretty effusive. What made this eruption more serious was that there are towns on the volcano’s slopes, right in the path of the eruption. Fagradalsfjall was a tourist sight; this is what it could have been if it had been a few miles in another direction with the lava heading straight for Hafnarfjörður, for example. This is a sudden reminder that this pretty thing, this natural novelty, is actually a destructive force of nature that can’t be stopped or contained. By more luck than anything, only one person was killed in this eruption and Wikipedia says “the cause has yet to be determined”. I’ve not been to the Canary Islands but they’re on the list – in winter please, polar bears do not thrive at those latitudes – because they’re so volcanic but this has given me a thonk on the head to say “do not treat these things lightly”.
Up another gear. Earthstorm volcano 3 is Masaya in Nicaragua which is rated 5 on the VEI. Masaya hasn’t erupted in a major way for 1800 years but that doesn’t mean it’s not active. It has a lava lake bubbling away in the bottom and that has overflowed twice in the last five hundred years and the crater has had a couple of explosions in the last 30 years. Scientists are monitoring it, although our understanding of volcanoes is so little at the moment that all we can really say is things like “something has changed. Maybe that means the volcano is getting more active?”.
So off Earthstorm went to Fuego in Guatemala which erupted in 2018, to show what Masaya could do if it suddenly decided to erupt. Fuego was destructive and lethal – 200 people killed officially, another thousand at least who are either still missing or whose deaths haven’t been attributed to the eruption. This time it wasn’t the lava that caused the death and destruction, it was pyroclastic flow. You know when you see a huge plume of smoke and ash coming out of a volcano? Well, sometimes those things collapse under their own weight and it begins to run across the ground. Often, obviously, it collapses onto the side of the volcano and then runs downhill with gravity helping it pick up speed. These things are heavy – thousands, millions, of tons of ash and debris and that gives it incredible momentum. You can’t outrun a pyroclastic flow. I was astounded that this documentary showed people successfully out-driving it because a pyroclastic flow can move far quicker than a car when it wants to.
A pyroclastic flow destroys everything in its path. That’s partly because it’s a mass of rock and ash moving at up to 200 metres per second – that’s 447mph – and partly because it’s incredibly hot. It’s probably hotter than the lava flow and that’s hot enough to melt rock. This is hot enough to vapourise rock. I don’t think there’s anything on the planet more destructive than a pycroclastic flow. It’s what took out Pompeii and Herculaneum in 79AD – not lava, but a collapsed ash cloud which moved so quickly that some of the petrified bodies evidently didn’t have time to notice it was coming.
I mentioned cars out-driving this cloud of death. That’s the most horrifying part of Earthstorm, seeing people with cameras racing for their life, leaving people on the side of the road because there’s nothing they can do to save them. You know because the footage is on Netflix that they survived themselves but with that thing chasing them down the road, you do find yourself wondering: will they make it? Am I going to see these people die, consumed by the monster? It’s terrifying. Remember back when we were oohing and aahing over the fire fountains at Fagradalsfjall? Doesn’t it look like a newborn pet kitten compared to Fuego’s pride of rabid starving lions now?
But the worst is to come. Campi Flegrei, nightmare fuel. Campi Flegrei is a supervolcano, a colossal underwater caldera sitting underneath Naples. Vesuvius, destroyer of two cities, looks like a primary school science project in comparison. Campi Flegrei is active – there are hotspots under the water, volcanic gases are bubbling up to the surface from it and it’s distorting the seabed above it, making it slowly rise up and down as if the volcano is breathing and it’s responsible for the sinking of the Roman town Baiae, which is now about five metres under the bay of Naples and is possibly Atlantis. Campi Flegrei, supervolcano, is rated 8 on the VEI.
Now is a good time to explain the Volcanic Explosivity Index. It’s a logarithmic scale. You might think an 8 is twice as powerful as a 4. No, it’s worse than that. For every number you go up, the explosivity increases by 10. A VEI 8 is ten times as explosive as a VEI 7. A VEI 7 is ten times as explosive as a VEI 6. And so on and so on. Except when you get to the bottom end. VEI 3 is ten times as explosive as VEI 2. But VEI 2 is a hundred times more explosive than VEI 1. Let’s do the sums. How much more explosive is Campi Flegrei than Fagradalsfjall? 1 up to 8, which is currently the highest the scale goes up to, although it’s not impossible a supervolcano can blow the scale out of the water. Anyway, 1 up to 2 = 100, 2 up to 3 = 10, 3 up to 4 = 10 and so on and on on until we get to – 100,000,000. Campi Flegrei is one hundred million times more explosive than Fagradalsfjall.
If Vesuvius erupts, it could potentially kill or at least affect three million people. If Campi Flegrei erupts, it will vaporise everything within at least a fifty mile radius and wipe a chunk of Italy off the map. There will be nothing left but a smoking crater. That’s how big this is. That’s how terrifying this is. Europe would be plunged into the sort of volcanic winter where storms not seen in human history would ravage the land, the temperature worldwide would plunge by at least four degrees, crops and livestock would be destroyed, Europe will experience famine on a scale never seen before, ash and debris will choke people’s lungs and the rest of the world will experience probably a decade of misery before most of the ash settles. Something underwater that size will send shockwaves across the planet – because of the bottleneck in the Mediterranean between Spain and Morocco, southern Europe and north Africa will probably have spectacular tsunamis and the east coast of the Americas smaller ones which will still cause a certain amount of destruction. It will be a disaster beyond our current conception of disaster.
That’s the bad news. Let’s make it worse. Europe has two VEI 8 supervolcanoes. The other is sitting under the water just north of Santorini. There are more in the western USA – you know of Yellowstone but it’s not the only monster in the region. There’s a cluster of them somewhere around the Argentina/Chile/Bolivia border, a few dotted along Indonesia, a couple south of Japan, a couple on the Russian Kamchatka peninsula and one on New Zealand’s North Island.
The good news is that Campi Flegrei hasn’t erupted for 40,000 years. It’s unlikely to wake up just yet. And the world’s most recent supervolcanic eruption, in New Zealand, happened 26,500 years ago. They’ll happen again in the future but I don’t think there’s too much risk of imminent world-destroying eruptions in our lifetime – or indeed, in humanity’s lifetime. I’m going to be optimistic about how long the human race has and even being optimistic, I think the sleeping supervolcanoes will outlast us. I’m no volcanologist; I am a person who prefers to stick her fingers in her ears and sing la-la-la, the volcano isn’t going to get us, but I genuinely think these things are few and far between. We know of sixteen that have happened in the entire history of the planet. The earliest we know of was during the Ordovician epoch. You know the Jurassic? You know how long ago that was, when there were dinosaurs? Well, the Ordovician was as long ago as then. Sixteen times in 400 million years means an average of 25 million years between supereruptions. That means we’re 24.9 million years off the next one. I reckon we’ll be ok.
So that was Earthstorm: Volcano. A lovely start building to a horrifying end. If you want to know more about Supervolcanoes, I’ll immediately be ordering Super Volcanoes: What They Reveal About Earth and the World Beyond by Dr Robin George Andrews who I’ve followed on Twitter for a couple of years and is a wonderful accessible science writer who loves to explain why the media is wrong. That link is to bookshop.org, by the way, and is an affiliate link so if you click it, they’ll give me a few pennies.
