a recurring apocalypse
Feels a little reminiscent of The Cabin in the Woods. Which, well, is what we have here too.
But what gets me is it's stated that this happens here and there through history (I don't believe it's specified how often). The issue with that is that you'd assume that most people wouldn't just jump on board with the idea of the sacrifice immediately. Meaning that they too would wait until examples started happening, like the tsunamis and so on. And they all presumably have given in since the apocalypse has been averted. So, it seems like it'd be known in-story that every now and then in history, there's been a random day where everything just goes wrong like that. And you'd think maybe someone in the past would've come forward about their part in it.