Rock glue?

[tengu1]

Hi there

So beardie has decided under her rock is the best place to sleep. I have a smaller rock on the ground and a bigger rock on top. This gives her basking at different levels for obviously hotter or cooler basking. Also she loves clambering all over it. Anyway I didn't think she would also love sleeping under it. I worry because being in Japan earthquakes are more often than I would like so I have to glue these rocks together in case it falls on he during the night.

Which glue is for this. I know there is aquarium glue but all sites say for fish.

Any advice, links are appreciated

Thank you