By Chris Post
It’s a common zombie trope: the undead creature bursting forth from their grave, having clawed its way to surface. But could they really do it?
In a word, no. While the image is a great one for film, the truth of the matter is that being buried is a pretty permanent scenario, especially today. In the end, it boils down to two factors: burial practices and weight.
Although not required by law, many cemeteries require the use of burial vaults. Although they can take a variety of forms, from plain to elaborate, all vaults are essentially the same thing: a concrete box to house the casket.
Vaults are used for several reasons, both pragmatic and emotional. First and foremost, the vault keeps the surface of the grave from becoming concave when the coffin at the bottom rots and collapses. Vaults also give the living peace of mind that their loved ones aren’t becoming an all-you-can-eat worm buffett.
Regardless, the presence of a vault would make it all but impossible for a reanimated corpse to escape its casket. But what if there wasn’t a vault? Even then it would be very difficult.
Because human hands are not designed to claw and dig, it would be hard for a zombie to scratch its way out of the casket, even if it was just of the plain pine box variety. A modern casket would be even more difficult given the reinforced nature of their construction.
By the time the casket would be rotten enough to aid in the escape, infiltration of water and the aforementioned worms and insects would mean there would likely be little left of the zombie.
A body buried without a casket might be able to escape the grave but even this would likely be impossible. Assuming that the zombie is not granted some sort of super strength, the weight of dirt alone would likely be enough to keep it in place.
Topsoil free of rocks and other large debris weighs between 1,700 and 2,000 per cubic yard, depending on moisture content. A standard grave plot contain about 2.6 cubic yards of dirt above the casket, meaning the weight pressing down on the zombie would be somewhere in the neighborhood of 4,250 to 5,000 pounds.
Obviously, the shallower the grave, the less dirt and therefore less weight will be pressing down on the zombie. So the lesson here is double tap and burry them deep.