Cathedral officials have written a letter to Cologne Mayor Jürgen Roters to notify him of potential damage to the city's world famous building, the Kölnische Rundschau newspaper reported on Wednesday. The mayor promptly called a crisis meeting with the local transport authority, the KVB.
Though the train tunnels near the cathedral were first dug several years ago, the tremors were noticed on December 9, the day that the city's No. 5 underground line first went to the new Dom/Hauptbahnhof station.
The vibrations were confirmed by an earthquake measuring station, which has five sensors inside the cathedral.
Cologne's nearby philharmonic concert hall has reported similar problems since new underground train tracks were installed.
Two people were killed when the city's historical archive building collapsed in 2009 and a subsequent inquiry blamed mistakes made at a nearby underground train track construction site.
Cologne Cathedral, the construction of which took over six centuries to complete, is one of Germany's most popular tourist sites, attracting six million visitors every year.