The Washington Monument, one of the grand attractions in Washington, D.C., will be closed indefinitely, the National Park Service announced Monday.
In August, a 5.8-magnitude earthquake caused more damage to the monument than had previously been disclosed.
Video taken by a security camera during the earthquake showed the monument shaking violently and debris falling from the structure. The scene left visitors scared and running for cover, but there were no injuries caused by the incident. A copy of the video can be seen at http://www.nps.gov/wamo/washington-monument-earthquake-update.htm.
The external damage the monument suffered during the earthquake was compounded by internal damage. Large pieces of stone have fallen inside the monument and an elevator inside the building is in need of repair. An official with the Park Service said the elevator could not ascend to the top of the 555-foot tall monument and is now only able to reach the 250-foot level.
A preliminary assessment of the damage revealed some cracks in the stone that allowed water to penetrate the structure when Hurricane Irene passed through Washington days after the earthquake. This allowed a substantial amount of water to enter the structure.
But the worst damage occurred in the pyramidium, which is the pyramid-shaped capstone at the top of the monument.
“Daylight is visible at a number of the vertical joints where mortar is missing,” Mall superintendent Bob Vogel told The Washington Post.
Park officials said a rappelling operation will begin immediately and will take about five days. Engineers will be harnessed and hang from ropes while they tap on each exterior stone.
“You can tap it lightly, and the stone density will make a definitive sound,” Dan Gach, one of the rappelling engineers, explained to The Washington Post.
He said engineers use the tapping method to detect problems. “That area will just sound dead,” Gach said.
Construction of the historic monument began on July 4, 1848, and was completed in December 1884. It cost a little more than $1million to build. More than a half-million visitors tour the monument each year.