The restoration of San Pedro cliff at the Alhambra, an example of the preservation of historic sites

An example of the problem of hanging towns is San Pedro cliff, a dihedral 65.5 m high, which has progressed to place itself at a distance of 23.8 m of the wall-palace of La Alhambra that is a Heritage of Humankind. A deep research has shown that active normal faults surrounding the cliff have created an extension tectonic regime that loosens the ground and activates the ground falls. The factor of safety of the cliff subject to the 1000 years return period earthquake is 0.73. The preservation solution proposed is a post-tensioned high elastic limit wire mesh and autochthonous vegetation. With this reinforcement, the safety factor under that earthquake raises to a value around one. In this way, the environmental impact is negligible.