The first five albums are set in an isolated human planetary colony called Aldébaran, which (we are told on the first page) lost contact with Earth long ago. Our central characters, 17-year-old Marc and 13-year-old Kim, witness peculiar things happening in the ocean near their village, and then - as promised in the title - catastrophe destroys their homes, and the story switches to odyssey format as the two of them travel to, and beyond, the distant metropolis.
Although the setting is much the same as one might get in a traditional hard sf novel, the execution is very different; the bande dessinée tradition concentrates much more on character and dialogue than on technology and Being Smart. The tech we do have is almost but not quite streampunkish, with motor vehicles apparently made of wood and a mad professor type who turns out to be rather banal in his nastiness. The human and physical landscape clearly owes a lot to the author's native country - Marc and Kim's home village appears to be pretty multi-ethnic, though it's less clear if that is true of the city; the jungle is a place of risk but not deadly danger; distances are vast but not unbridgeable.
I'll certainly keep going with this series. The French, thank heavens, is manageable - a fair bit of subjunctive but I was able to cope, and the vocabulary is all pretty obvious. And basically I want to find out what happens next.