On August 23, 2011, the monument was damaged by a magnitude-5.8 earthquake. The heaviest damage was to the top of the monument, known as the pyramidion. Along the rest of the monument, masonry on all four sides also suffered damage.
WSP, along with Hill International, was chosen by the National Park Service to provide construction management services during the repair process.
The National Park Service commissioned the repairs to be done in several ways:
- Loose fragments were secured with adhesives and anchors drilled into the backing of the stones.
- Missing stones were filled with exact-fit pieces and reinforced with mortar and rods.
- Cracks were filled with epoxy-based adhesives and then sprinkled with limestone dust to hide the cracks.
- Damaged lime mortar was taken out and replaced so water can flow off the monument instead of getting caught in the stones.
The iconic national landmark, which was encased in scaffolding and closed to the public during repairs, reopened in May of 2014.