Safes often include rubber pellets in the concrete pour between steel casing layers. Cutting into the safe with a torch or plasma cutter will cause these rubber pellets to burn and fill the room with noxious odors and thick smoke.
It doesn't necessarily increase the physical resistance to entry, but it makes the environment extraordinarily unpleasant.
I also like the breakdown they have of the different levels of communication. I can easily see it being mapped to product design- easy to digest information at the top of the funnel, more detailed/important information as you approach the bottom of the funnel.
Also even if poisoning people was ethical, how would the poison last 10,000 years? And how would you prevent people from using the poison as the potent weapon it clearly is? And what would the message be for those who defeat the poison to find the treasure that's obviously hidden by such a potent weapon?
This question is hard because you can't assume we'll be a technologically advanced society; for all we know, we'll be living with stone age technology.
[1] http://www.chinadaily.com.cn/china/2010-09/09/content_112783...
Leave a fraction of the radioactive unshielded and buried less deeply, to ensure that wannabe grave-robbers die of radiation poisoning before they uncover much of the cache?
(a) We have all become very marker-prone, but shouldn't we nevertheless admit that, in the end, despite all we try to do, the most effective "marker" for any intruders will be a relatively limited amount of sickness and death caused by the radioactive waste? In other words, it is largely a self-correcting process if anyone intrudes without appropriate precautions, and it seems unlikely that intrusion on such buried waste would lead to large-scale disasters. An analysis of the likely number of deaths over 10,000 years due to inadvertent intrusion should be conducted. This cost should be weighted against that of the marker system.
The problem is that this was during the Cold War, and the site needed to operate on an ongoing basis, not just be used once and then hidden. They had to prepare for the possibility of a Soviet nuclear attack killing everyone responsible for the site, thus had to design a site which would still serve even if its operators disappeared.
I immediately think of Oak Island, Nova Scotia, where a pirate's stash has resisted recovery for an incredible 221 years but has yielded taunting clues:
There are layers of wood, etc, but they're probably just laid down by natural causes over the millennia instead of being a constructed building.
Flagstones, layers of heavy timbers every 10 feet, a stone with carved glyphs at 90 feet, oak chests with coins, a sideways booby-trap well, Layers of blue clay at 130 and 160 feet, a cofferdam, and artifacts dating back 200+ years.
This strikes me as far, far more than an elaborate prank; it is a significant defense system meant to protect _something_
The flooding tunnel is likely just a normal geological feature, not some super-clever drift tunneling technique.
The stone is likely a fraud. Who would place a cryptic sign 90 feet down, telling themselves (in secret writing) to keep digging? Wouldn't they presumably know that they hadn't reached their treasure yet? Wouldn't they be more likely to place an innocuous sign on the surface, such as a gravestone? It's more likely a way to con investors out of further funds.
It's probably nothing but a rumor.
The point is to hide the waste. The system should be designed to progressively unveil warnings if some future man starts digging. Otherwise, you're just asking for them to dig it up.
Another thing not mentioned is to design the container so that anyone who plans to excavate will think they have hit rock bottom... like Pharoahs' tombs or a multi-level pirate cache.
Or even better, put something horrible and poisonous twenty feet down. It might be better to obviously poison a couple people if they start digging this up. That would be easily understood and eventually avoided.
Remember the radioactive sign in the Star Trek episode where Data gets shishkabobed? They made jewelery...