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In your answer, Please Exclude:
1.a Yellowstone Supervolcano eruption
2. a giant super-tsunami from a La Palma eruption,
3. a meteor/comet impact a gamma ray burst or any other cosmic cataclysm.

These things are scary for sure but they're a bit cliche. (Besides, this topic is grim enough without those quasi-apocalyptic scenarios)
Also, feel free to include actual natural disasters that did not live up to their worst case scenario. There have certainly been plenty of terrible ones over the years.
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