Do you have Bach’s Rescue Remedy or perhaps some lavender aromatherapy oil? Or is it at least something you can get a hold of?
Both are known to calm down animals.
I think perhaps, I would cover up a bit of the condo, where he is hiding, so it feels like an underground tunnel. That might make him feel more calm.
Also, once the quakes pass, it will help. We had a big earth quake here last year or so, and my cat felt it about 30 seconds before it came. He panicked completely and when I ran over to him to figure out what was wrong and calm him down, then it came. So animals can sense these things so much better than we can, and the earth is still unstable after the quake, so perhaps he can feel this.
I never can figure out the time of the posts here, so I don’t know if I am days behind with my advice. But if you live in an area with quakes, it might be a good idea to stock up with rescue remedy at least