Fennoscandian Land Uplift


There has long been knowledge about the Fennoscandian land uplift. Residents of Sthammar City began to complain in 1491 that the previous harbor could no longer be used because the shoreline had moved too far from the city. The phenomenon was well-known throughout the Gulf of Bothnia beaches, where new land was emerging from the water and the existing harbors were rendered useless. Anders Celsius, one of the most well-known early uplift experts, calculated an uplift value of 13 mm/yr close to the city of Gävle in the early 1740s. He did not comprehend the reason for the increase, despite the fact that the amount in Celsius is rather near to the current value. Instead, it was believed that the phenomena, rather than the uplift of the land are caused by a lowering of the water.

Sea level variations relative to the coast can be observed using sea level gauges, such as tide gauges (mareographs) or less complex water height scales. Sea level measurements in Stockholm started in the 1770s, first using a water scale. Two years after the oldest mareograph in Finland, at Hanko, a permanently recording mareograph was erected. The mechanism and cause of land uplift were only discovered when Gerard de Geer released the Fennoscandian land uplift map in the late 1800s and when at the same time the phenomena brought on by the Ice Age were researched.

Through frequent, accurate leveling, the height variations distant from the sea can be observed. The first national leveling took place between 1892 and 1910; the second, between 1935 and 1975; and the third, between 1978 and 2006. The continuous leveling has made the land uplift well known throughout Finland. The leveling campaigns in the other Nordic nations were similar, and Fennoscandia as a whole is well aware of the uplift. GNSS stations can now be used to continuously monitor crustal motions. One can observe the horizontal movements brought on by the uplift using GNSS.

The Quark region experiences the fastest land uplift, at around 1 cm per year. The Southeast portion of Finland has the smallest uplift, with a speed of less than 3 mm per year. Going to St. Petersburg makes it impossible to see any upward movement.

The Earth's crust was sunk by half a kilometer as the ice, which was 2 kilometers thick, receded from Fennoscandia more than 10,000 years ago. The crust started to rise after the ice melted, and recovery is still ongoing. There are still about 100 meters to rise towards the Gulf of Bothnia, where the ice was the thickest.

One effect of the global glacial phenomenon is the uplift of the land. The Earth's crust and upper mantle are both impacted by the Glacial Isostatic Adjustment (GIA), as are changes in gravity, sea level height, and the glacier cycle. The Earth's shape changes, its mass distributed differently, and its mantle experiences a gradual mass flow all at once. Even on the scale of the entire Earth, the glaciation-deglaciation cycle, which lasts 100,000 years, results in a sea level change of more than 100 meters. Up to 51019 kg of mass has been transferred in total; this is over one thousandth of the mass of the Earth. Massive glaciers expand and shrink, squeezing and releasing the Earth's crust. This has continued for at least the last two million years.

North America, the northern hemisphere, Fennoscandia, and northwest Russia all experienced the greatest intensity of the previous Ice Age. These locations' uplifted terrain reveals a glacial past. The ice age is still going on in Antarctica and Greenland.

Sea level rise is caused by melting glaciers. The rate of sea level rise is currently around 1.5 mm per year, but it has roughly doubled in recent years. The observed pace of land uplift is slowed down in coastal locations due to sea level rise. New land will still rise from the sea since the sea level rise is now less rapid than the uplift rate along the Finnish coast. The phenomenon is particularly obvious along the Gulf of Bothnia shore.

Because of frequent accurate leveling and GNSS readings, the rate of land uplift in Finland is exactly known. The uplift process and its impact on gravity change and uplift specifics are still not entirely understood, though. The land uplift and sea level rise along our shores are studied by the Finnish Geospatial Research Institute.

Fennoscandian land uplift has a long and rich history, including early observations of its effects on harbors and coastal villages. Even if its real explanation was still obscure at the time, Anders Celsius's groundbreaking work in the 18th century laid the groundwork for understanding the phenomenon.

A crucial turning point was reached with Gerard de Geer's discovery of the process underlying land elevation and its link to the Ice Age in the late 19th century. Land uplift is now a well-recorded phenomenon in Fennoscandia thanks to subsequent national leveling initiatives and the use of GNSS technology.

The complicated geological mechanisms at work are illustrated by the different rates of land uplift observed throughout the region, from the quick rise in the Quark region to the slower uplift in Southeast Finland. The terrain is still changing as a result of the Earth's crust continuing to rise after the ice retreated, which caused it to sink by half a kilometer.

Aside from affecting land uplift, the Glacial Isostatic Adjustment (GIA) also has a significant impact on gravity, the height of the sea, and the glacier cycle. Over millions of years, this event has significantly shaped the Earth's surface.

The rate of sea level rise brought on by melting glaciers has accelerated recently, having an effect on coastal locations. Fennoscandia, on the other hand, is experiencing land uplift that is outpacing sea level rise, which has led to the development of new land along the shore of the Gulf of Bothnia.

There is still much to learn about the complexities of land uplift and sea level rise, despite the fact that we have made great progress in our knowledge of these phenomena. We will be able to better understand these geological processes and their significance for our changing planet as a result of ongoing study conducted by organizations like the Finnish Geospatial study Institute.


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