“A rescue op. Save the dinosaurs from an island that’s about to explode. What could go wrong?”
These are the words of Owen Grady, Chris Pratt’s character in the trailer for Jurassic World: Fallen Kingdom, and as you’d expect, things do go gloriously, spectacularly wrong. What we weren’t expecting was that, at one point, Grady would have to outrun a pyroclastic density current from an erupting stratovolcano, one that eventually catches up to him – and a bunch of dinosaurs – before presumably knocking him off a cliff and into the sea.
We’re assuming he survives, because otherwise, that’s a hell of a plot spoiler to drop into the trailer. That, of course, made us wonder: what the hell is going on? Can Chris Pratt almost outrun a pyroclastic density current? Can any dinosaur? We weren’t entirely sure, so we asked a volcanologist and a palaeontologist to shed some much-needed light on all this.
Full disclosure: there’s a good chance we’ll thoroughly enjoy this movie. No, we don’t care that there’s no friction in space – Star Wars space battles are awesome. Similarly, we won’t care that Chris Pratt survives a volcanic eruption like this. As long as the movie isn’t 2012, Geostorm, or Volcano, we’re cool.
First things first. What kind of pyroclastic density current (PDC) is it? There are several, and some may make it less likely that Grady meets a grisly end. Take it away Jess Phoenix, a volcanologist who also happens to be running for Congress.
“You cannot outrun a pyroclastic flow. You cannot survive in one. Abandon all hope, ye who enter here,” she enthuses.
“Many good scientists have been killed by pyroclastic flows, most famously Maurice and Katia Krafft on Unzen in 1991. They were experienced volcanologists, something which Pratt's character is definitely not.”
Owch. Burn to Grady there, in more ways than one.
“Incidentally, why on earth would anyone locate a major tourist attraction on an island that is literally nothing but a giant volcanic hazard zone? That's just madness,” Phoenix ponders. Apparently, it’s for the boundless geothermal energy available to them – but still, whoops.
Anyway, yes. Pyroclastic flows are the classic PDCs. Traveling at speeds of 80 kilometers (50 miles) per hour – and often far faster – they form when an entire, or part of, an eruption column collapses, usually when the violent depressurization of the magma source dies down, or when the column cools enough to become somewhat dense.
Sometimes, you get weird flows that move as slow as 18 kilometers (11 miles) per hour, but these are incredibly rare – and the one in the trailer clearly is moving far quicker. So let’s discount these ones.
Within them, mixtures of ash, lava blebs, and superheated gas can reach temperatures of up to 1,000°C (1,832°F), and even the air around them can be pushed up to several hundreds of degrees.
Forget the average; the top human running speed is 45 kilometers (about 30 miles) per hour. Grady is not Usain Bolt, so it’s unsurprising he gets caught up in the movie’s pyroclastic flow. His skin would boil and rupture, his muscles would violently contract, he'd quickly asphyxiate and, as occurs in some instances, his brain would boil and his skull would explode.
Grady doesn’t die though, which suggests to Phoenix it’s “a pyroclastic surge”, a PDC where the ratio of gas to debris is far higher. These are sometimes so “light” that they’ve been seen flowing up hills and across water. They’re often cooler than flows, but she points out that “it would still be anywhere from 200°C to upwards of 982°C (390°F to 1,800°F)” on the inside.
“Doesn't seem likely that he'd be able to outrun a flow even in the best of circumstances,” Phoenix concludes.
Crispy Chris Pratt it is, then. What about those dinosaurs? Franzi Sattler, a palaeontologist and evolutionary biologist at the Free University of Berlin, has some thoughts.
“There are definite constraints when it comes to what determines how fast an animal, in this case, a dinosaur, can walk or run,” Sattler tells IFLScience.
“It depends on how big it is, and there is no way a 30-tonne sauropod can run with its entire, massive body weight. So you can bet that a large animal, running at a max speed of a few tens of kilometers per hour, couldn't survive this.”
There are a few smaller, sprightlier animals in the trailer though, and they appear to stand a better chance of outrunning the pyroclastic flow.
“These two-legged ornithopods are estimated to have been able to run a lot faster, but their body plan is also very different,” Sattler adds. Really though, you’d definitely need to be warm-blooded.
“If you want to run super fast, and not just for a sprint, but for a longer time (as you probably would when you try to outrun a pyroclastic flow) then you must generate a good supply of metabolic energy.
“So really, if you start far away enough from the surge already, survival rates depend on whether the dinosaur is warm-blooded or cold-blooded,” Sattler points out. “Pro tip: be warm-blooded.”
The palaeontological jury is still out on which dinosaurs were warm- or cold-blooded, but it appears the latter in this case stood an even lower chance of making it out alive.
Sattler suggests one dinosaur may have had a chance: the Dromiceiomimus. This is a genus of “bird mimic” beasties, and some research has suggested that they could reach top speeds of 80 kilometers (50 miles) per hour.
“We don't know 100 percent how fast these dinosaurs have been able to run, but since the body plan is similar to ostriches, with long, muscular legs, this is not a bad guess,” she explains. “Ostriches can apparently run up to 70 kilometers [43 miles] per hour – pretty good, but even they might be screwed in this scenario, really.”
Pterosaurs, those non-dinosaurian flappy nightmares, would be alright though. “They can just zip off into the air, right?” Sattler adds, disdainfully.
As pointed out by a rather splendid post over on Discover, there are plenty of other strange volcanological goings on in the trailer. When it comes to the aspect of simply outrunning a pyroclastic flow on Isla Nublar, though, you’re doomed.
Life, uh, doesn’t find a way this time.