Comment by cjbgkagh

No genius needed, but all those involved are motivated to lie about it. The bombs have a depth range and 200ft (60m) is the optimistic depth for ideal conditions. These were far from ideal conditions as the location was specifically chosen to resist this. That and ultra high performance concrete is now a thing. This is why the entrance and exists were bombed and those are easy enough to dig back out again. The attack was telegraphed so advanced preparations were made. It is rumored that the entrances and exits were packed with dirt in advance to minimize the damage.