Well, I would think that if fracking is able to create earthquakes, a hurricane with the huge movement of water, and subsequent adjustment of load could have an impact.
If the city had been built below sea-level - an insane idea on an island - then a hurricane could easily, and permanently flood it, for the water would have no place to go. Now, if the ground beneath the city was riddled with mines, its possible the flooding could add enough weight to collapse the mines and drop the city deeper.
Amethyst occurs in rocks with volcanic or igneous origin, so the ground beneath the city would be quite strong unless it was heavily mined, contained extensive open spaces (empty magma chambers) or both. Perhaps the island itself is an extinct volcano. Go to Comment
Perhaps it is nothing to do with roots. Real oaks count on squirrels to spread their acorns, so at first the squirrels happly spread the acorns. However, since they are not nutritious they eventually all starve. Once there are no squirrels nearby, the spreading stops unless happenstance - water, humans, spreads one to where squirrels can again carry out their duty:) Go to Comment