Millions of pilgrims travel to the Church of the Nativity in Bethlehem each year, particularly at Christmas, because of its historical and religious significance as the site of Jesus' birth.
Dante Fratta was unlike most tourists visiting the site. He brought ground-penetrating radar and electrical resistivity equipment.
Fratta, an associate professor at the University of Wisconsin-Madison, was part of a team called to the West Bank town to learn buried secrets of the church without lifting a shovel. After a recent archaeological excavation in a section of the church known as the Hall of St. Jerome, authorities worried about the structural integrity of the church, built in A.D. 339.
That prompted the survey by an international team of experts from Peru, Portugal and the U.S. last summer. Fratta, an expert on near surface geophysical techniques, was asked to join the project.
"It was a neat experience," Fratta said. "I'm not religious, but this is the center of many religions of the world. We had opportunities to go places tourists don't go. I consider myself very lucky to have the opportunity."
Fratta is adept at using ground-penetrating radar to send electromagnetic waves into the ground and wait for reflections that can detect the presence of nails or water or other substances, as well as evaluate walls and rocks. The equipment measured the depth of the foundations of the columns down to the bedrock to help evaluate the church's stability and provide more information about the underlying geology for future excavations.
The team spent a week in July at the Bethlehem church, measuring as much as they could to protect the fragile structure from further damage. They placed sensors, measured vibrations and scanned surfaces with lasers, installed a network of sensors for long-term monitoring of the church and created virtual 3-D maps of the Hall of St. Jerome, detailing cracks and damage.
"The challenge of this site is that construction has been going on for more than 1,000 years. You see at different depths different types of construction and foundations _ a wall that was built by the Crusaders, a wall built 500 years ago _ which is very difficult to evaluate. Technically, that's been the challenge for us," Fratta said.
Fratta's research at the site showed there's quite a bit of limestone that's fairly close to the surface underneath the Church of the Nativity. Most of the buildings in Bethlehem have a yellowish tint because they were built or fabricated with the abundant limestone.
A church was first built at what is believed by some to be the site of Jesus's birth by Constantine the Great and his mother Helena. The original basilica was destroyed by fire in the 6th century. A new basilica was built by the Byzantine emperor Justinian in 565 and was used as the primary coronation site by Crusader kings in the 1100s. The church has undergone many construction and restoration efforts since then.
In 2010 Palestinian authorities announced plans for a multimillion-dollar restoration of the Church of the Nativity, but called a halt to the digging when excavators came dangerously close to undermining the support beneath a structural column in the Hall of St. Jerome, named after the man who translated the Bible from Hebrew and Greek into Latin.
Four denominations oversee the Church of the Nativity _ Roman Catholic, Greek Orthodox, Armenian Apostolic and Syriac Orthodox. Even though the Hall of St. Jerome is under the auspices of the Armenian Church, all four churches need to grant approval for the team's survey.
Fratta said the team recommended retrofitting one of the columns in the Hall of St. Jerome to improve the integrity and stability of the church.
