As a reader pointed out, this is not a picture from Canopus, but from the Licorne shot.
It has been fired at 18.30 on July 3, 1970, and yielded 914 kilotons, quite less than Canopus, but still impressive and dreadful.
Although this picture, like many of the series, is a work of the French Army (as far as I know) this is an original scan from a hardcopy I posess, and processed to remove dust and scratches.
A strange view on such paradise-like landscapes.
Reddited : reddit.com/info/2zf6d/details
And thank you for your comments, they're appreciated :)