An atomic bomb dropped from a plane would seem to be the only answer.
3 seconds sound clip from Radar Men from the Moon - Hills of Death (S1E6).
You can hear this line at 00:05:30.111 in the Blu-ray version of the movie.
Quote context
[...]
- Very well. Then start an intensified campaign with the ray gun.
- Earth's defenses must be completely broken down before we can risk an invasion from the moon.
- At once. I will get you the bomb.
- If the moon men did start that eruption, they certainly got results.
- An atomic bomb dropped from a plane would seem to be the only answer.
- You know, Commando Cody thinks that maybe...
- I think we're on the right track.
- Then we're right. They're the ones who bombed the volcano.
[...]