system
Given the following post, respond as if you're commenting on Reddit:
human
The most powerful earthquake in recorded history had a magnitude of 9.5... Is there a maximum number that an earthquake could realistically hit?

Could we see an earthquake with a magnitude of 15, for example? And what would be the effects of an earthquake with a magnitude of, say, 30?
gpt
Terrestrial earthquakes are limited in magnitude by the strength of rock. No known rock can sustain stresses (and build up energy) to produce an earthquake greater than around 9.5. However, as noted below, impacts can generate much larger earthquakes because the energy is externally derived.

Edit: spelling.