Although it has been publicly called a record karst sinkhole, there is currently not enough data to confirm its origin or connection to natural karst processes. According to the initial assessment by LGT specialists, it may be a technogenic-suffosion collapse, meaning its formation could have been influenced by human activity or underground structures. Specifically, a 120 m deep underground water well operated near this collapse, which was decommissioned in 2007.
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What is mechanical suffosion?
Mechanical suffosion is a geological process where flowing underground water washes out fine particles of clay, silt, or sand and carries them to another free space. Over time, a cavity forms in the soil, and the layers above lose support, causing the ground surface to sink or suddenly collapse.
For suffosion to occur, there must be not only a water flow but also a space or channel into which soil particles can be transported. Such conditions are sometimes created by leaky underground pipelines, wells, boreholes, or other man-made structures.
A suffosion collapse can externally resemble a karst sinkhole, but these processes occur differently.
During karst processes, underground water dissolves soluble rocks, such as gypsum or dolomite, forming underground cavities.
In mechanical suffosion, the rock is not dissolved – fine soil particles are simply washed away.
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Further research needed
Geologists emphasize that to accurately determine the origin of the collapse in Buiviškiai village, archival geological and technical information must be collected and analyzed. Geophysical studies, such as electrical tomography, should also be conducted to assess underground soil density and detect possible disturbed zones or cavities.
If the technical condition of the well allows, it is advisable to examine its construction. Only after these tasks are completed will it be possible to confirm or rule out the well’s influence.
LGT will update the information when geologists, conducting fieldwork for karst landscape condition monitoring in October and November, inspect this phenomenon on site. After gathering more data, more precise conclusions about this collapse and other karst-related geological hazards will be published.
The collapse formed near a cultivated field. According to available data, it does not pose a direct threat to residents or buildings, but approaching it is not recommended as the edges of the collapse may be unstable.
