WASHINGTON (CNN) -- A seismic study found that the Washington Monument can withstand a worst-case earthquake scenario, officials said Thursday, August 24th in describing needed repairs to the iconic landmark damaged in the 5.8-magnitude quake a year ago.
The 555-foot monument will be under full scaffolding for repairs to damaged marble plates, stonework and other problems near the top, said Bob Vogel, superintendent of the National Mall and Memorial Parks.
Vogel offered no time frame for the repairs. Officials previously said the monument could be closed through 2013 and possibly into 2014.
The monument has been closed since an earthquake struck the mid-Atlantic region near Richmond, Virginia, on August 23, 2011. Vogel said more details of the repair work would come next month.
A comprehensive seismic study determined the monument faced no risk of collapse, even in the event of a "maximum considered earthquake," the estimated worst possible quake over a 2,475-year period, Vogel said.
Such a scenario "did not present a concern for structural collapse," he said, adding that "supporting soils are indeed adequate to withstand" a maximum considered earthquake.
At least nine marble panels on the outside of the monument near the top are cracked, according to a post-earthquake assessment. Others are chipped but not in danger of falling, the report said.
About 700,000 visitors go to the top of the monument in a typical year.
Indoor repairs are also required. Some interior tie beams and some cracked panels will be fixed.
The Washington Monument was built between 1848 and 1884 and has been repaired three times previously, the most recent work done from 1997 to 2000.