Personally I would think active geology at the cost of burned trees would be more Maud Pie's (or any non-Pinkie member of the Pie family) thing more than Applejack's. Also, I'm trying to imagine Applejack becoming a (space) explorer and it doesn't quite fit. Maybe the local Lava Demons(1) are having a Friendship problem like they did back in G1 and the map called her? Or maybe this scenario, but with slightly improved communication (so clearer earlier) and/or a longer/later eruption: https://www.fimfiction.net/story/542235/volcanoes-are-our-friends . EDIT: Or maybe that is the next erruption to happen somewhere on Equus, and Apple jack is bionding with Maud at the site.
(1) Yes, they were actually called that in G1!
(1) Yes, they were actually called that in G1!