Magnetic storms wars .. earthquakes are big on my list. Currently living right on the Vancouver islands fault line that is more then 500 years over due for a large Earthquake that repeats its self every so many years.
If it happened now according to a University geologist we could have a Dam break and Great Central lake a 33km / 20 mile long 333M / 1000 foot deep Man Made lake pour down a mountain and over town .Lucky for me Im at the far end of town furthest away from the Lake of all the homes
Edit to add : My house is 150 feet up a hill side with the Ocean and town 150 feet below me