Distortion
In this subject one has to consider any departure from vertical or from horizontal and by how much such departure has taken place and where. E.g.: if the floor is no longer level and slopes downwards in one particular direction and that direction points at a nearby tree, then one can suspect such a tree. Alternatively, some walls may be leaning over and other walls built parallel to them may lean likewise in the same way. Subsidence of one of the outside leaning walls becomes suspect.