system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can you test a nuke underground but on the surface it would be devastating?

If a nuke would explode on the surface of the earth it would be super devastating for the nature, for humanity etc. but underground its ok and nothing happened like earthquakes, the radioactivity?? Why?
gpt
When a nuke explodes underground, the mass of the ground absorbs most of the impact, and radioactive remains mostly stay in the crater. It's not powerful enough to create an actual earthquake, though the seismic wave can be registered.

When it explodes on the surface or in air, the shockwave (hot compressed air) is free to travel around, demolishing everything in its path. Radioactive dust also spreads much easier this way.