This is where it gets personal.
The third Yoko Tsuno adventure, La Forge de Vulcain was published in 1973, and it is also the first Yoko Tsuno story I ever read, when I was about 9 or 10 – therefore, in 1976 or ’77, when it was published in Italian. The book was later published as the ninth English-language Yoko Tsuno volume, as Vulcan’s Forge.

Re-reading this about 45 years after the first time, I was impressed by how sharply I remembered some details – the Vinean jet changing configuration, shifting from standard atmospheric flight to vertical descent into the depths of the ocean and then the earth is probably what got me hooked.
But really, reading Vulcan’s Forge at such a young age clearly had consequences.

The story takes the Curious Trio to Martinique, where a Shell drilling platform has struck some unusual material – a material that Yoko recognizes as some of the mysterious metal used by the Vineans in episode #1. We soon find out that the drill perforated a pipeline built by the Vineans and carrying magma. The mix of molten rock and gas (what the Shell crew is here to tap) might cause a big blast and a tsunami, and potentially trigger an extinction-level event. Yoko (with Vic and Pol in tow) must join the Vineans in trying to set everything straight, and fast.
But a political change has taken place after episode 1 – no longer governed by a sociopath AI, the Vineans are now a somewhat fascist regime, led by the second-fiddle bad guy from episode 1, Karpan.
A dissident pro-human faction exists (mostly composed of Vinean women), but they are treated as traitors and terrorists.
So yes, this is a ego-engeneering adventure, with an extra of political intrigue and action, courtesy of the Vinean faction that is OK with exterminating humans.

This is a very hard-SF, tech-heavy comic book adventure – we get a lot of geophysics and geology, as we explore the caverns in which the Vineans live, complete with Verne-style giant mushroom forests and the remains of dead dinosaurs.
We get the usual expository passages and technical footnotes, and the mecha-design is as always absolutely top notch. – and we get to see a lot of Vinean hardware. The design of the drilling platform is also very fine and highly realistic.
This is a very hard-SF, tech-heavy comic book adventure – we get a lot of geophysics and geology, as we explore the caverns in which the Vineans live, complete with Verne-style giant mushroom forests and the remains of dead dinosaurs.
We get the usual expository passages and technical footnotes -this is supposed to be, in a way, educational or inspirational.

And as I said this is becoming personal, because 10-years-old me was getting heavily into volcanoes and dinosaurs at the time, and so maybe Yoko Tsuno had a hand in pushing me to pursue a career in earth sciences. And, I mean, why not?
And I did later work for Shell – something that might be controversial today (oil companies are not as environmentally concerned as they appear in this comic) but that contributed to make me what I am today.

Thankfully, Vic and Pol are out of the way for most of the adventure, while Yoko gets to meet a few characters from episode #1.
The character design is rapidly shifting to a classical Ligne Claire look(*), and for a young readers’ story this one looks like a million bucks. We are about to take a step back with the fourth volume, but for the moment, everything looks great.

(*) I think maybe I might need to do a post comparing the Marcinelle and Ligne Claire styles of Franco-Belgian comics. Supposing someone’s interested.