Just remember folks for pole shift doom:

Air tight container buried no more the 3 ft under the ground but with anchor weights to keep it under water In-case the magnetosphere goes down shortly . In a pole shift the water might stay over you.Make sure you have a way to release the anchor weights from the container so it will float to the top .When the ocean gets more then 20 ft high over you it will pop out the ground a float with only 3 ft of dirt.Pole shift are normally complete within 48 hours .

Nuclear doom: you need more then 3 ft of dirt on the top of the container.