Järkumisfaase

Järkumisfaase is a specialized concept used primarily in Estonian structural geology and engineering literature to describe a distinct stage in the lifecycle of natural or engineered geological formations. The term succinctly captures the phase during which a landform or a constructed structure experiences pronounced oscillatory movements and incremental destabilisation, often as a precursor to major morphological change or failure. In mountainous terrains, for example, the järkumisfaase is characterised by episodic uplift and subsidence that manifests as fault scarification, rockfall activity, and surface erosion patterns distinctly different from the earlier gentler erosion stages. Engineers employ the concept in assessing post‑construction stability of slopes, wharves and embankments, where irregular load conditions may induce rhythmic deformations before a settling or consolidation regime is reached.

Identifying the järkumisfaase typically involves time‑series geophysical monitoring, such as tiltmeters and GPS networks, combined with visual inspection of scarification marks. The duration of the phase varies widely: in soft sedimentary contexts it may last a few years, whereas in crystalline bedrock it can extend into several decades. Accurate delineation of the järkumisfaase allows scientists to predict subsequent landform evolution and to design mitigation measures for infrastructure that overlaps active geological boundaries. Related concepts include the pre‑catastrophic destabilisation phase, the consolidation phase, and the long‑term regressive erosion stage, all of which form part of a broader erosion‑flood–reclamation cycle in geomorphological theory.