Early indications are that a collapse of a subway tunnel station still under construction was to blame for the sinkhole that destroyed Cologne's Historical Archive, home to documents dating back to 922 A.D. More info after the break. (Photo by DPA via Spiegel Online)
The collapse occured last Tuesday afternoon. The staff working in the Archive were able to escape before the building collapsed after sounds of the structure buckling were heard. One body was recovered and one additional person was thought dead but was still missing. The collapse also heavily damaged several surrounding appartment houses as well. The heaviest part of the tunnel construction was supposedly completed 1-year earlier, but the tunnel floor had not been finished. The tunnel and station has been a controversial project in Cologne, with problems occuring as early as 2004 when a church steeple began experiencing tilt of 77-cm, greater than 15 times what was predicted.
The archive was Germany's largest municipal archive, and the only one to survive World War II completely intact
Aerial view of the collapse of Cologne's Historical Archive, thought to be related to an underground subway station and tunnel still under construction. (Photo by DPA via Spiegel Online)
It is of course too early to tell exactly what caused the collapse, but in a recent Spiegel article, they reported on an "unnamed source" who commented on the possible cause of the collapse:
Quoting an unnamed source close to the investigation into the accident, the Kölner Stadt-Anzeiger reported Monday that the tragedy was likely caused by ground water seepage at the construction site. "Everything points to a problem with the ground water," the source told the paper. City prosecutors have now appointed several experts to determine exactly what happened at the underground railway construction site. They are trying to determine whether water seeped in through the more than one-meter thick concrete side wall or came up through the floor, which hadn't been finished. They are also looking into whether the problems might be related to rising levels of the Rhine River, which is located very close to the archive.
Source: Spiegel Online via ASCE Smart Brief.