The Earth Story

What does Volcano (1997) get wrong? Like, I'm well aware that the guy that jumps and ends up basically doing the Terminator 2 thing (melting into the lava) is very wrong and that there's no way for the LA area to have a volcano, but I wanna see you explain it.

Alright, I’m biased because I love that movie. But truthfully, it actually does a good job of being accurate besides a few points.

1) The heroic concrete K-rail scene would have failed spectacularly. Concrete begins to fail structurally at around 300°C/572°F, whereupon it begins thermal expansion. Water evaporates and the cement shrinks, but the aggregates continue to expand. This contradicting action puts a lot of stress on the internal structure.  At 573°C/1,063°F, the quartz in concrete undergoes rapid expansion, and at 900°C/1,652°F, the calcite starts to shrink due to decomposition. At 450-550°C/842-1,022°F, the cement hydrate decomposes, yielding calcium oxide, and calcium carbonate decomposes at about 600°C/1,112°F. Fresh pahoehoe lava, as seen in the movie, can reach 700-1,200°C/1,292-2,192°F. The k-rails would have been destroyed. There are also pretty sizable gaps between the k-rails. Pahoehoe lava flows easily, it would have just oozed through the cracks.

Also, lava doesn’t flow into a single direction. Just because they stopped a flow on that street doesn’t mean the lava will stop flowing down other ones…

2) Heavy ash fall is depicted throughout the eruption. Nobody is choking or having difficulty breathing despite being covered in it. Volcanic ash is like microscopic glass shard. Breathing it in shreds the sinus and lungs, and mixes with mucus to produce a heavy slush that can choke animals to death. Ash also re-solidifies in car and aircraft engines and destroys the mechanical parts. All the cars and helicopters would have been unable to operate in the heavy ash, and yet they worked fine.

3) You would think the premise of a volcano just randomly appearing out of nowhere is absurd, but it’s actually possible and has happened before. The Mexican volcano Parícutin suddenly birthed out of a poor Dionisio Pulido’s corn field in 1943. Los Angeles sits on a transform fault, which is not commonly a source of volcanism, but it is not impossible. The only beef I have with the sudden volcano is that it would not have erupted from a tar pit. Tar pits are not geologically active, they’re simply petroleum deposits that leeched to the surface. The odds of a hot spot appearing under one are pretty slim.