The island of Pulau-Pulau Bompa is the fictional volcanic island that appears in Flight 714. I’m in the process of updating the Tintin Map and I’m trying to get a better fix of where the island might be, or at least what island Herge based it on.
We know that it is a small island, with an active volcano. We can also assume that it is some way from other land otherwise the building of the airstrip and the landing of the hijacked plane would of been spotted. Tintin & co was rescued 200 mils off their planned route (Page 60, frame 1)
One candidate is Banda Api. It is a 3km wide island with the volcanic peak of 640m above sea level. According to the Global Volcanism Project’s entry on the island, it last erupted in 1988 and in 1902 prior to that. It position and appearance certainly fit Flight 714 but it is too close to other land.
Nila, another island in the region is a very likely candidate. A 5×6 kilometer island with a 781m peak, this island last erupted in 1968 (the year Flight 714 was published). Prior to that it erupted in 1964, about when Herge would be starting to work on the book. That eruption was a phreatic explosion, a highly explosive type of eruption similar to the one that destroyed Mount St Helens. Nila has two twins, Serua and Teon. Neither has erupted since the 1920s.
There are many other possible volcanic islands in the region but most are near other islands. The area is one of the most active volcanic regions on the planets and every year, one or more of the volcanos will erupt. Which, if any, inspired Herge we don’t know but I think Banda Api is the closet fit to the physical appearance and but Nila fits the location better.