I'd do it a little differently. If a house is destroyed by any form of reasonably common widespread disaster it becomes illegal to build anything on that lot t

I'd do it a little differently. If a house is destroyed by any form of reasonably common widespread disaster it becomes illegal to build anything on that lot that would likewise be destroyed. You can rebuild after the hurricane, you must build a house that will stand up to a hurricane. (Yes, it can be done.) I wouldn't apply this to flukes--your town does a Tunguska there's no reason to require asteroid-safe houses. I would also make an exception for things which by their nature must be in the line of fire--such things must never be permanent habitation and can't have community-rate insurance against whatever happened to them. A business can rebuild it's beach cabanas but would have to go to Lloyd's if they wanted insurance.