Repairs could cost up to $5 million and extend into next year, officials said. But the extent of the damage will remain unknown until crews can reach the cracks and test them. It is nearly 100 feet to the top of the main dome.
A preliminary review suggests that the damage is limited to restored plaster that was part of the nearly $40 million renovation completed six years ago, and is not structural, said archdiocese spokesman Sean Caine. But there are about 50 cracks that are expanding in the main dome and two saucer domes.
"My heart dropped when I saw the first one," said Monsignor Arthur F. Valenzano, the rector. "I wondered if it was there all along and I had just missed it. But then, others began pointing out more and more."
Starting in June, the historic structure on Cathedral Street will be closed weekdays for the repairs — a move that will mainly affect visitors drawn to the neoclassical building designed by Benjamin Henry Latrobe, the architect of the U.S. Capitol. The archdiocese expects to open the Basilica of the National Shrine of the Assumption of the Blessed Virgin Mary for weekend Masses and for 21 previously scheduled weddings that will likely be conducted below scaffolding.
"We have to address the damage and deter any further deterioration," said Doug Johnson, manager of capital projects for the Archdiocese of Baltimore. "We are hoping most cracks are cosmetic, but we are treating them as if they are structural. This is all fixable."
The 5.8-magnitude earthquake that shook the Mid-Atlantic on Aug. 23 damaged several church properties, including the National Cathedral in Washington and St. Patrick's Church in Fells Point, which sustained nearly $2 million in damage when its steeple toppled.
Soon after the earthquake, the strongest to hit Maryland in memory, the archdiocese ordered inspections of all its properties and found damage to 44 buildings, including the basilica. So far, the cost of those repairs has exceeded $1 million. It looks as if the basilica, the latest earthquake victim, will be the costliest to repair.
The cracks appeared soon after the earthquake and have steadily grown. Repair is essential to preserve the integrity of the dome, church officials said.
Those who look up at the basilica's imposing domes, filled with 24 newly uncovered skylights that flood the building with natural light, might detect the cracks that angle downward and in some cases, cross the ceiling and archways.
Engineers have assured church officials that the building is safe and poses no threat to those worshiping within its walls.
"I am concerned but not worried about the safety of the building," Valenzano said. "We have a wonderful professional team, the same ones who worked on the restoration. They are same skilled craftsmen we used the first time. This is a chance to touch up."
That touch-up might extend into repainting the entire ceiling, contractors said.
Henry H. Lewis Contractors will send the same team that spent two years restoring the church to tackle repairs. "The team is emotionally invested and familiar with the structure," Johnson said.
During repairs, tours will be curtailed or possibly restricted to certain areas outside the main church, Caine said. The neoclassical structure drew 135,000 visitors last year.
"Tours will be curtailed at best during the work," Caine said. "They will be canceled at worst."
Weddings, Catholic high school graduations and weekend Masses will go on as scheduled.
The basilica staff has contacted all 21 brides, and only one has opted for a change of church. The graduates can still walk up the center aisle, without dodging scaffolds, and some 600 worshipers attending any of four weekend Masses should have an unencumbered view of the altar, Caine said. The parish is home to about 400 families, who come from all areas of the archdiocese.
But the church, which usually keeps its doors unlocked throughout the week, will be closed from Monday through Friday.
"We have been blessed with tourists, the curious, the architectural students and historians," said Valenzano. "For some this is like visiting a museum."
The final cost of repairs will depend on what engineers find beneath the cracks, Johnson said. Given the size, age and height of the basilica, the archdiocese included earthquake damage in its insurance policy and hopes to recover much of the cost. Repairs could run from $3 million to $5 million, officials said, depending on what engineers discover.
The scaffolding will go up June 1, and crews will work first on the main dome.
"That is the highest off the ground and it probably shook the most," said Johnson. "That's the location of the most cracks," Johnson said.