At 1:51 p.m. on August 23, 2011, a magnitude 5.8 earthquake struck 90 miles southwest of Washington, D.C. Visitors inside the Washington Monument's observation deck were thrown about by the force of the shaking; falling mortar and pieces of stone caused minor injuries, though all the people inside exited safely.

The most significant modern damage to the Washington Monument, including over 150 cracks, was caused by a 5.8-magnitude earthquake that struck on August 23, 2011. The quake's epicenter was near Mineral, Virginia, but the tremors were felt strongly in Washington, D.C. The shaking caused the 555-foot stone obelisk to sway violently, leading to structural cracks in the stone blocks, particularly near the pyramidion (the pointed top). Debris and mortar were shaken loose, and some stones were actually displaced. Following the earthquake, the monument was closed for nearly three years for an extensive $15 million restoration project. Engineers used specialized rappelling teams to inspect every inch of the exterior, sealing cracks with epoxy and installing metal "Dutchman" patches to reinforce the marble. While the monument had faced minor issues in the past—such as lightning strikes and settling of its massive foundation—the 2011 earthquake remains the primary event responsible for the prominent cracking and the subsequent modernization of its internal support and elevator systems to prevent future seismic damage.