First off, I think you are confused on what it means to "survive" something. Those people who have lived after jumping out of a plane...did you ever seen the medical reports? They would be paralised from the waste or neck down, fractured every bone in their body, have major internal bleading and possibly brain damage. However, once put on life suport they are still alive. Thus they have "survived".
Survived =/= Unscathed
And the people who rode down Niagara, stop using them as excuses. The ones who survived were engineers who designed there pods and procedures to not drown or get injured during the fall plus water when fallen correctly offers better support than a hard rocky cliff side. Look up Houdini next time bucko.
The lead lined refrigerators are the same bi-product of the "duck and cover" method...it was invented to keep a paranoid society from breaking apart. A comfort blanket, they did not actually work. The only way to survive is to wait a maximum two weeks in and underground bunker fortified with hard/shock absorbent materials.
In fact, it would have been more believable if Indy happened to find a home made bunker in the test town. That would have been in character too, because Indy is skilled at looking for secret passages in the first place.
But overall, this whole thing is a bi-product of a new age of society that has grown up on science. (Note I am not condemning it, in fact I support it.) You cannot show us stuff anymore, you have to at least explain it to us that would make sense in a believable way. Then we will accept the spectacle.
Its one of the reasons why the recent Batman and James Bond films are doing so well in the first place!