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Deforming Earth

The Solid Earth is being deformed constantly due to changes in the load by the atmosphere, oceans, and continental water storage. The crust under our feet rises, sinks and tilts, and also gravity is always changing. At short time intervals (from seconds to years), the Earth’s response is elastic, while at longer time intervals (from hundreds of years to millions of years) the Earth reacts like a highly viscous liquid. Typical phenomena that cause variations during short time intervals include ocean circulation and the redistribution of atmospheric and hydrologic masses. A well-known long-term change in Fennoscandia is post-glacial rebound, that is, the land uplift after the load by the Ice Age ice masses disappeared.

The Finnish Geospatial Research Institute has been observing the motions of the crust using different measuring techniques. Vertical and horizontal movements are detected in GPS time series; the superconducting gravimeter at the Metsähovi observatory measures the gravity change and the water tube tilt meter in the Tytyri mine in Lohja measures the change in the tilt. GRACE, which is a satellite that observes the change in gravity, does not directly measure the movements of the crust; rather, it measures the attraction of the mass load causing the changes and the change in the gravity field of the deformed solid Earth.

Environmental effects mean the effects caused by changing masses of atmosphere and continental water storage. They can be seen in e.g. superconducting gravimeter.

Water tube tilt meter measures the change in the tilt of the crust.

Post-glacial rebound is visible in all geodetic measurements that are conducted over several years.

Loading by Baltic Sea discusses the crustal deformations in Scandinavia due to changes in the water mass of the Baltic Sea.