Was Isla Nublar, Jurassic Park, Destroyed?
There was a cutscene with Peter Ludlow (The infamous board room scene) that tells you that Isla Nublar had been demolished. Now that also raises the question of should we count it as part of the movie? Yes we should because it and the bar scene with Roland and Ajay were shown in the film when it aired on FOX for the first time. Another reason is to explain the focus on Sorna as well. Now it would also make sense to have Nublar demolished by the Costa Rican government for fear of the dinosaurs reaching the mainland. We know Hammond basically guarded Sorna with his life and it was probably assumed that Hurricane Clarissa wiped out the dinosaur inhabitants of Isla Sorna.
