In the middle
Meter-long, deep cracks can be found in parts of the Worms synagogue. The reason for the problems is apparently the dryness of the soil as a result of climate change. The building should now be saved using careful methods.
First you go all the way up the ladders of a scaffolding, into the vault of the Worms synagogue. Architect Jürgen Hamm shows what endangers the stability of the monument. He points to a large crack: “You see, I can get my hand into this crack, it goes along the vault, and that’s why it’s supported here with wooden scaffolding.”
The cracks in the vault and parts of the walls of the sacred building don’t just look oppressive to laypeople. “You don’t see cracks and crack systems like that very often, that’s really a sign that you absolutely have to do something now and immediately,” explains architect Hamm, who is responsible for the restoration of the synagogue on behalf of the city of Worms. In the worst case scenario, the vault could collapse and the north wall could collapse.
Even from the outside it becomes clear how deep the wound in the world heritage is. A crack in the main portal of the synagogue runs from the vault through the window arch down to the foundation. It is meters long and around 80 centimeters deep. “The crack is not just on the outside, the wall is completely torn through,” explains Hamm.
UNESCO World Heritage since 2021
Cracks have existed in the Worms synagogue for a long time, but almost three years ago they became so large that those responsible had to take action. On behalf of the city, architect Hamm secured the synagogue with steel beams on the outer walls. Steel cables are stretched between them and run through the interior of the monument and hold the synagogue together.
The synagogue has been a UNESCO World Heritage Site since summer 2021. The first Jewish church was built in Worms in the Middle Ages, and the synagogue was last rebuilt after the Second World War. It symbolizes almost 1,000 years of Jewish history in Germany, including persecution, destruction and reconstruction. That’s why preserving the Jewish religious community is particularly important.
“This ambiguity, on the one hand, to say that it is an incredibly fruitful story, a symbiosis that had many, many blossoms and, on the other hand, the terrible tragedy. All of this is visible in this building, and that is why the efforts are made to create this Preserving buildings is very necessary for me,” says Peter Waldmann. He is deputy chairman of the Mainz-Rheinhessen Jewish Community.
The Worms synagogue currently needs to be secured.
The situation worsens during hot periods
Despite the emergency securing with steel beams and cables, architect Hamm and the responsible monument authority have to constantly keep an eye on the cracks in the synagogue. A first observation: the situation worsens in hot and dry periods. “The cracks actually got bigger, even got bigger incredibly quickly, so we had to constantly re-tighten the steel cables,” explains Hamm.
The cause of the problems is believed to be beneath the synagogue, far down in the ground. Archaeologists are therefore carefully removing the various layers of soil. The masonry that is revealed dates back to the Middle Ages. There are even suspected remains of the first synagogue from 1034 here.
Bettina Gransche from the responsible monument protection authority in Worms emphasizes the importance of the historical foundations. “This is a valuable historical soil archive here that we absolutely must preserve. It also tells the long story of destruction and reconstruction.”
Dryness as a cause
Jürgen Hamm also says that this is a piece of history that is being uncovered here. But what interests the architect above all is something else. The synagogue stands on a layer of clay. And that’s exactly where the problem lies. “When it gets very warm, the clay layer shrinks and becomes smaller, and when it is damp, it swells again. This is due to the clay changing its volume.” Movements in the ground are the result. For months, an expert has been measuring the moisture levels in the ground beneath the synagogue and comparing them with the crack movements.
Georg Maybaum is a professor of geotechnics and comes to the conclusion: There is a clear connection here. “The claim was that the drying out of the soil, which has something to do with climate change, is a major influencing factor in the formation of cracks in the synagogue. And I think that can be proven with the measurements.” The ground is sometimes drier, sometimes wetter, and he can correlate this with the increase or decrease in the size of the cracks in the synagogue.
Georg Maybaum, professor of geotechnics, sees a connection between dryness and crack formation.
Secure carefully for the future
Stabilizing the foundations of the sacred building with concrete, for example, is out of the question for monument protection reasons. The world heritage requires careful restoration. One consideration: a targeted irrigation system. “You can do it the same way you know it in horticulture, drip irrigation,” explains Maybaum. “When the ground is wet we stop and when the ground is dry there are a few more droplets.”
Whether the synagogue’s structural problem can really be solved in this way will only become clear next year at the earliest. Those responsible in Worms want to do everything they can to save the synagogue and its historical foundations. “After this long history of destruction and reconstruction and the Shoah, we obviously don’t want to lose this synagogue to climate change,” says Bettina Gransche from the Lower Monument Protection Authority in Worms.
In any case, the emergency safety measures give the city time to carefully prepare the world heritage site for climate change. However, the steel structure is not a permanent solution.