WASHINGTON (AP) -- Engineers will begin rappelling down the sides of the Washington Monument on Tuesday to check for cracks and other damage from the surprisingly strong East Coast quake last month.
Numerous cracks and chips were found inside the iconic national landmark after the 5.8-magnitude quake Aug. 23 that rattled the capital and the region from the border with Canada to the Georgia seacoast.
The Washington Monument remains closed indefinitely to visitors because of the damage and the National Park Service said Monday that there's no timetable for reopening the tourist attraction or for completing repairs.
Dozens of pieces of stone fell in the interior of the monument during and after the quake, and park service officials said they need to make sure the obelisk is safe before the public is allowed back in. Security camera footage made public Monday showed startled tourists scrambling after the quake violently shook the monument's 500-foot-high observation deck.
"The good news: The monument is structurally sound and is not going anywhere," said Bob Vogel, superintendent of the National Mall and memorial parks.
Speaking at a news conference, he and other officials said they hoped to provide a timetable for repairs by mid-October.
The exterior inspection is expected to take five days. Once it's completed, the park service will begin winterizing the monument -- essentially plugging any cracks with caulk or other sealants to keep water out.
A helicopter inspection the day of the quake revealed a 4-foot-long, inch-wide crack in the pyramidion, the part at the top where the monument begins narrowing to a point. Follow-up inspections detected several smaller cracks in the pyramidion. From some spots inside, it's possible to see through to the outside, and the monument took on water in recent storms, officials said.
Stephen Lorenzetti, deputy superintendent for planning for the National Mall and memorial parks, said the park service hopes to avoid erecting a scaffold around the monument like that required during the last major renovation between 1998 and 2000.
He noted that hard mortar on the exterior was replaced in 2000 with a softer substance. Had the harder mortar remained in place, the monument probably would have sustained more extensive damage, Lorenzetti added.
He also said it was possible that the monument could reopen while repairs to the exterior were ongoing.
Also Monday, the park service released surveillance videos from the observation deck that show the monument shaking violently for more than three minutes. One video shows more than a dozen visitors scrambling for cover as they are showered with debris and a park ranger hurries them down a staircase.
"I was freaking out -- didn't know what was going on, didn't know what we were experiencing," the ranger, Nikolette Williams, told The Associated Press on Monday. "But my first thought was, I had to get the visitors down the stairwell and into the bottom of the monument as fast as possible."
Williams said it took about 10 minutes to get everyone down the stairs and no one was seriously injured though one woman suffered a cut on a hand from a falling piece of stone.
Neither Williams nor Park Police Officer Matthew Cooney realized at first that an earthquake was shaking the monument.
Cooney was on the ground and saw the top of the obelisk swaying as he, another officer and visitors were pelted with falling mortar. He quickly ran up the staircase to help visitors at the top and told AP that he thought the monument would topple with him inside.
"I absolutely thought it was coming down -- 100 percent," Cooney said.
Engineers assessing the damage are from Wiss, Janney, Elstner Associates Inc., of Northbrook, Ill., a firm specializing in earthquake damage. Its work so far has cost about $207,000, officials said.
The 555-foot-tall white marble monument was completed in 1884 and had never been damaged previously by a natural disaster, including a stronger earthquake in 1897. The tallest structure in the world at the time, its still the tallest in Washington.