Property Rights: Avoid Landslides and Subsidence
One landowner’s use of her property may involve excavating and altering the earth on the surface or underground. A landowner may want to level her sloped property to make it more useable for certain purposes. She may dig into the earth to build structures on the land. She may excavate under the surface to extract valuable minerals.
Excavating and altering the land in these ways may affect adjoining and nearby lands. Leveling a slope on one’s land may remove lateral support for adjacent land uphill, causing the hill to slide downward and possibly damaging buildings on the adjacent land in the process.
Excavating on the surface likewise may cause the adjacent land to subside because of the loss of lateral support. Excavating underground may remove subjacent support, support of the land from underneath, thus causing the surface of the land above to subside and fall down.
Property rules address such conflicts and decide who bears the cost of avoiding such damage and paying for such damage that isn’t or can’t be avoided. The common law rules differ depending on three variables:
Whether the support is lateral (from the side) or subjacent (from underneath)
Whether the removal of support would damage the land in its natural condition or damages the land only because of the additional weight of buildings on the land
Whether the damaged land is adjacent to the excavated land or just nearby
Laterally supporting adjacent land in its natural state
A landowner has a property right to the naturally existing and necessary lateral support from adjacent land. That means that each landowner is strictly liable for any damages resulting to adjacent land because of removing lateral support necessary to support the land in its natural condition.
It doesn’t matter how careful the landowner is or how valuable her use of the land. A landowner also is entitled to an injunction to prevent removal of naturally necessary support by an adjacent landowner.
This rule doesn’t mean that landowners can never excavate their land if it would remove naturally necessary support. Not only could they negotiate with the adjacent landowners for the right to excavate, but they also can provide the necessary support by artificial means, such as retaining walls.
As long as an owner continues to provide the naturally necessary support in some way, she hasn’t interfered with the adjacent landowner’s property right to support of the land.
Most authorities agree that a landowner is liable for damage only if she removes earth that is naturally necessary to support the adjacent land. If she excavates on her land and that causes water or oil to flow out from the earth, which causes adjacent land to subside, she generally isn’t liable.
Even though a landowner only has the property right to support of her land in its natural state, an adjacent owner who removes that support is generally liable for all damages that result, not just the damage to the land.
Most courts agree that if the damaged land has buildings and other improvements on it, the foreseeable damage resulting from interference with the property right of support includes damage to the improvements, so the one who removed support is liable for those damages, too.
Laterally supporting nearby land and improvements to land
Most courts seem to agree that a landowner doesn’t have an absolute duty to maintain naturally necessary support for land that is nearby but not adjacent to her own. However, she is liable for damages if she negligently removes support for nearby land.
Likewise, a landowner doesn’t have a duty to support the additional weight of buildings and other improvements on adjacent or nearby land. Even so, many courts hold that a landowner is liable for negligently removing support for buildings. Removal of support may be negligent in the following circumstances:
The removal of support is unnecessary for the landowner to use her land as she wants.
The landowner removes support without giving adjacent and nearby landowners notice so that they have time to protect their properties from possible damage.
The landowner removes support without taking reasonable precautions to minimize damage to other properties.
The landowner removes support carelessly, not using reasonably careful techniques or not using appropriate equipment to perform the excavation in a way that will minimize the risk of damage to other properties.
Supporting land from beneath
Ordinarily, the owner of the surface owns the earth underneath, too, so her subsurface property supports her surface. But sometimes the ownership of the surface may be severed from subsurface ownership. In that situation, the subsurface owner may remove support necessary to sustain the surface owner’s land, such as by excavating to remove minerals.
As with lateral support, the general rule is that a subsurface owner is strictly liable to the surface owner for removing naturally necessary subjacent support. Some courts go further, however, and hold that the subsurface owner also has a duty not to remove support necessary to sustain buildings and other improvements that were on the surface at the time the subsurface estate was severed from the surface.
In either case, the subsurface owner certainly doesn’t have to provide support for improvements made after severance. However, as with lateral support, the subsurface owner is generally liable for any damages that result from removing the support that the surface owner is entitled to.
So if the subsurface owner removes naturally necessary support or support necessary to sustain improvements preceding severance, she’s liable for all resulting damages, including damages to improvements made after severance.
Courts presume that subsurface removal of support would cause the land to subside regardless of the weight of improvements. So to avoid liability the subsurface owner must prove that the land wouldn’t have subsided if it weren’t for the improvements on the surface, or the improvements added after severance.