Ok I have a little experience here😬.
We have found that talking during the day about the mechanics of natural disasters and giving kids a concrete plan of what to do in an emergency helps. Also talking about the engineering sid of things helps. Obviously you can't guarantee safety and hopefully it will never be an issue but I think some kids just want to know that yes it is scary but the adults in their life have got it sorted. There are a lot of child friendly resources out the about earthquakes in particular if you preface Christchurch into your google search.
