The situation is the worst in the center on Raekoja plats where the uneven surface resembles a moonscape.

Toomas Haidak, deputy head of the Tallinn Urban Environment and Public Works Department, told Thursday's "Aktuaalne kaamera" that the weather plays a role.

"In particular, there will certainly be frost heaves [when the ground swells with ice – ed.], and to some extent, there may also be soil scouring. It is estimated that this year there will be more than usual, perhaps due to the weather, but we can speculate that the foundations may affect the nature of the soil to make these frost heaves particularly pronounced," he said.

The agency said the subsidence has not affected nearby buildings, but as the problem also affects other areas, mapping started approximately a year ago.

Eero Kotli, Old Town Society board member, said Tallinn and the association are trying to find the cause.

"For example, at Tallinn City Theater, where a deeper excavation has been made and the water zone has certainly been crossed. It cannot be ruled out that the construction of a large casino on Rataskaevu tänav will also have an impact here," he said.

Haidak said the existing bumps will mostly be prepared by the summer.

"But in the longer term, Raekoja plats also needs a complete reconstruction. There is no separate rainwater drainage here, which is one of the reasons why water freezes under the surface. We are talking about a five-year perspective. Our next work will be on Pikk tänav /.../ and from there we would consider the reconstruction of Raekoja plats," he said.

Raekoja plats last underwent reconstruction 20 years ago.

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