Subterranean Caves and Lateral Support

Caves

The first thing that needs to be discussed is the ownership of caves that are beneath real property that is owned by a particular person. The general rule is that caves and/or subterranean property are inherently owned by the owner of the property above it. For legal purposes, ownership of real property extends downward from the surface of the property, in theory, to the center of the Earth. For example:

Old MacDonald had a farm. One day, Old MacDonald’s neighbor, Eieio, decides to dig a cave beneath his property to use as a bomb shelter. Later, it is determined that part of this cave was accidentally dug under Old MacDonald’s farm. Old MacDonald has full ownership right to that part of the cave. The fact that Eieio did all the digging and the fact that the only entrance to the cave is from Eieio’s property is irrelevant. The part of the cave below Old Macdonald’s property belongs to him. In fact, Old MacDonald can sue Eieio for trespass to land for digging into his property.

In addition, if a cave is discovered (rather than dug) under property, the cave inherently belongs to the owner of the property above the cave. If a subterranean cave lies beneath property owned by two or more people, but is used as a single entity then each property owner has a right to a share of the profits that the cave generates.

The next issue that must be addressed with regard to caves is the issue of support. This issue arises when one person owns the surface of the land and another person owns a cave or mine beneath the land. The rule, which, of course, follows common sense, is that the owner of the subterranean ground owes a duty of support to the owner of the land above the ground. In other words, the owner of the subterranean mine or cave must make sure that his or her mining activities or usages of the cave do not weaken or damage the property above. This duty of support is called the duty of “subjacent support.” For example:

Batman owns the Bat Cave, which is built directly beneath Alfred’s land. Batman owes a duty of support to Alfred. If Batman digs the cave so close to Alfred’s land that Alfred’s land shakes or that Alfred cannot bring heavy objects onto his land for fear that the ground will give way, then Batman has breached this duty.

See Large v. Clinchfield Coal Co., 239 Va. 144 (1990).

Of course, this duty extends only to reasonable usages of the above-ground property that existed at the time of the acquisition of the subterranean property. In other words, if there was a 5-story apartment building on the above ground property when the cave was bought, then the duty of subjacent support applies so that the subterranean cave owner cannot undertake an action that will jeopardize the stability of the building. However, if the property was designed for a single family residence when the cave was acquired and the owner decides to build an apartment building, the cave owner will not be bound to support the apartment building. For example:

Donald buys Blackacre. Beneath Blackacre is Silvermine, a mine owned by Walter that has been in operation for years. Blackacre has always been used as a farm. Donald wants to build a 25 story hotel on Blackacre and he insists that Silvermine cease to function, because its continued functioning will jeopardize the stability of his yet to be built hotel. Donald has no right to make this demand because Walter’s subjacent support duty only extends to reasonable uses of the land at the time that Walter purchased his mine.

Lateral Support

The other “support” duty arises between neighbors. The general rule is that adjacent land owners may not take any action that will jeopardize the stability of neighboring lands. If a neighbor does take an action that jeopardizes the stability of a neighboring land, the person taking such action will be strictly liable for any resulting damage. This means that the liability will attach even if there was no negligence involved in the action that caused the damage. For example:

Old MacDonald had a farm. MacDaffy owns property that is right next to Old MacDonald’s farm. MacDaffy builds a 100 foot building on her land. This causes the property surrounding the building to sag and it hurts the ability of MacDonald’s farm to produce. MacDaffy will be liable for this damage, even if her building the structure is not considered to be negligent.

If the adjacent landowner’s actions damage the structures on the neighboring property, there still will be liability for the damage. However, in most jurisdictions, there is no strict liability for damaging neighboring structures. Such damage only leads to liability if it was caused by the negligence of the builder. This generally would occur if the builder fails to account for the negative impact on neighboring structures that his building will cause. For example:

Donald has a 25 story casino on Blackacre. Ivana buys Whiteacre, a neighboring property. She builds another hotel on that property. The weight of Ivana’s building compromises the stability of Donald’s casino. Ivana will be liable, in most jurisdictions, if and only if she was negligent in building her structure. In other words, if she had no reason to know of the consequences of her building next door, she will most likely not be liable for the damages to Donald’s casino.

A minority of jurisdictions apply strict liability even for damages to structures on neighboring property.