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.