glacial isostatic adjustment - an...
TRANSCRIPT
![Page 1: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/1.jpg)
Glacial isostatic adjustment -An introduction
EGSIEM Summer SchoolPotsdam, Germany13/09/2017
Holger Steffen
With input from Martin Ekman, Martin Lidberg, Rebekka Steffen, Wouter van der Wal, Pippa Whitehouse and Patrick Wu
![Page 2: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/2.jpg)
2
GRACE observation, trend after post-processing
![Page 3: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/3.jpg)
3
1st EGSIEM GIA correction
![Page 4: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/4.jpg)
4
GRACE observation, GIA corrected
![Page 5: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/5.jpg)
Question: What word or term do you have in mind when you hear “Glacial Isostatic Adjustment”?
![Page 6: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/6.jpg)
![Page 7: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/7.jpg)
Time & length scale of some geodynamic processes
![Page 8: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/8.jpg)
8
GIA vs. the World
![Page 9: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/9.jpg)
� A bit of “GIA” history� Some physics
� Some applications
� Observations of GIA� Some applications
� GRACE, of course
PlanIn case of questions, ask!
![Page 10: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/10.jpg)
� Cathles, L.M. (1975) The viscosity of the Earth’s mantle, Princeton Univ. Press.
� Lliboutry, L. (1998) The birth and development of the concept of Glacial-Isostasy, and its Modelling up to 1974in Dynamics of the Ice Age Earth: a modern Perspective, Ed. P.Wu, TTP.
� Ekman, M. (2009) The Changing Level of the Baltic Sea during 300 Years: A Clue to Understanding the Earth, Summer Institute for Historical Geophysics, Åland Islands. Open Access Download: http://www.historicalgeophysics.ax/The%20Changing%20Level%20of%20the%20Baltic%20Sea.pdf
� Krüger, T. (2013) Discovering the Ice Ages. International Reception and Consequences for a Historical Understanding of Climate. Brill, Leiden.
Reference for historical development
![Page 11: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/11.jpg)
Northern Europe ca. 1635
(Source: https://upload.wikimedia.org/wikipedia/commons/7/73/Svecia%2C_Dania_et_Norvegia%2C_Regna_Europ%C3%A6_Septentrionalia.jpg)
![Page 12: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/12.jpg)
Luleå city/harbour relocation
8.8 km
5.7 km
1621
1649
1996
![Page 13: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/13.jpg)
(Source: https://upload.wikimedia.org/wikipedia/de/0/03/Karte_Gävlefischer.png)
Northern Europe ca. 1635
(Source: https://upload.wikimedia.org/wikipedia/commons/7/73/Svecia%2C_Dania_et_Norvegia%2C_Regna_Europ%C3%A6_Septentrionalia.jpg)
![Page 14: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/14.jpg)
(Source: https://upload.wikimedia.org/wikipedia/de/0/03/Karte_Gävlefischer.png)
Brämön
![Page 15: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/15.jpg)
(Source: Cornell University Library)
Athanasius Kircher, Mundus subterraneus (1665)
![Page 16: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/16.jpg)
(Source:https://sv.wikipedia.org/wiki/Anders_Celsius#/media/File:Anders-Celsius-Head.jpg)
Anders Celcius and Johannes Rudman
Johannes Augustini Rudman(1699-1760)
Anders Celsius(1701-1744)
?
![Page 17: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/17.jpg)
Seals rest close to the water surface
Saimaa ringed seal
(Source:http://www.sll.fi/mita-me-teemme/lajit/saimaannorppa/ringed-seal/leadImage)
Seal hunting(Carta Marina)
(Source: http://sydaby.eget.net/ody/opics/maps/saelfangst.jpg)
![Page 18: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/18.jpg)
(Source: https://upload.wikimedia.org/wikipedia/de/0/03/Karte_Gävlefischer.png)
View to Iggön
![Page 19: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/19.jpg)
Land uplift complicates seal hunting
1731
1563
237 cm
(Celsius 1743)
![Page 20: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/20.jpg)
Iggön 2015
![Page 21: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/21.jpg)
Iggön today
![Page 22: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/22.jpg)
(Source: https://upload.wikimedia.org/wikipedia/de/0/03/Karte_Gävlefischer.png)
Lövgrund
![Page 23: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/23.jpg)
(Bergsten 1954)
78 cm/100 a
Water marks: example Celsius rock
63 cm/100 a
![Page 24: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/24.jpg)
Water marks: example Celsius rock (08/06/2015)
![Page 25: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/25.jpg)
Water marks: example Celsius rock (08/06/2015)
![Page 26: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/26.jpg)
Water marks: example Celsius rock (06/15/2016)
![Page 27: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/27.jpg)
Water marks: example Ledskär/Ratan
![Page 28: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/28.jpg)
Uplift rate from water marks in Fennoscandia
(Steffen and Wu 2011)
Questions:� Did sea level fall or
did land rise?
� What is the cause?Land uplift
![Page 29: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/29.jpg)
Kettles/Potholes
Erratic boulder
Drumlin
Striations in bedrock
A step forward: Explain these structures!
![Page 30: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/30.jpg)
Structures are related to glaciers/glaciations!
� Alp valley inhabitants in the 18th century linked erratics to glaciers
� People knew that glaciers extended much farther before� Similar knowledge in South America� Many reported about that, e.g. Pierre Martel (1706–1767) in
1744, James Hutton (1726–1797) in 1795, Jean-Pierre Perraudin (1767–1858) in 1815
� Göran Wahlenberg (1780–1851) published in 1818 theory of a glaciation of the Scandinavian Peninsula, but interpreted as regional phenomenon
![Page 31: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/31.jpg)
https://upload.wikimedia.org/wikipedia/commons/3/37/Jens_Esmark.png
Jens Esmark (1763-1839)� Investigated glaciers and their
traces� Link erratic boulders and
moraines - glacial transportation and deposition
� Introduced 1824 concept that glaciers once covered larger areas (worldwide)
� Several ice ages related to orbital forcings
![Page 32: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/32.jpg)
https://upload.wikimedia.org/wikipedia/commons/e/e4/Ignaz_Venetz_1826_-_Wood_2014_p158.jpg
Ignaz Venetz (1788-1859)� Investigated glaciers in the Alps� Suggested in 1821 (but presented
in 1829 and published in 1833) that much of Europe had at one point in the past been covered by glaciers
![Page 33: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/33.jpg)
https://upload.wikimedia.org/wikipedia/commons/f/fe/Schimper_Karl_Friedrich_1866.jpg
Karl Friedrich Schimper (1803-1867)� Ice sheets once covered much of
Europe, Asia, and North America� Talked in 1835/36 about “world
winter” and “world summer” –climate changes
� Did not publish much, preferred to give talks
� So his findings were later popularized by…
![Page 34: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/34.jpg)
https://upload.wikimedia.org/wikipedia/commons/d/df/Louis_Agassiz-2.jpg
Louis Agassiz (1807-1873)� Investigated glaciers and their
traces� Presented 1837 the theory of a
past glaciation (”Eiszeit” – iceage) of large parts of Europe in a talk to Swiss scientists
� However, he was not the first (as shown on previous slides), buthis numerous subsequentpublications advertized thistheory, triggered furtherinvestigations and eventuallylead to acceptence of the ice age theory
� Theory expands in the British Empire & North America
![Page 35: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/35.jpg)
http://www.edinburghgeolsoc.org/images/z_40_02c.jpg
Charles MacLaren (1782-1866)� Realized in 1841 that sea level
must drop when the huge ice sheets formed during the Ice Age
� Estimated to be 800 ft lower (than in 1841)
![Page 36: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/36.jpg)
Now we have two things…
1. Sea-level fall/land uplift in northern Europe2. Ice age theory
Where is the link (or better, who makes it)?
![Page 37: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/37.jpg)
http://www.landforms.eu/ScottishSeaLevels/images/Thomas-Jamieson_small.gif
Thomas Jamieson (1829-1913)� Investigated sediments in
Scotland and found a sequenceof glacial, marine, terrestrial, marine, terrestrial sediments
� Concluded in 1865 that a glacier depressed the area, which wasthen flooded by the sea and later rose → link ice sheet – land uplift
� Did not use the word ”isostasy”� Later (1882) found that
depression relates to icethickness
![Page 38: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/38.jpg)
https://upload.wikimedia.org/wikipedia/commons/4/41/Picture_of_Nathaniel_Shaler.jpg
Nathaniel S. Shaler (1841-1906)� Reported in 1874 on the
changing shoreline of New England
� Made the same suggestion as Thomas Jamieson
![Page 39: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/39.jpg)
Let’s go back to this slide
(Steffen and Wu 2011)
Questions:�Did sea level fall or did
land rise?Land uplift!
�What is the cause?Former glaciation!
�Where was/is the land uplift?
�When was the glaciation?
�What are the underlyingphysics?
![Page 40: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/40.jpg)
http://sok.riksarkivet.se/sbl/bilder/17350_7_010_00000553_0.jpg
Gerard de Geer (1858–1943)� Varve chronology, the Swedish
time scale and glacial features (de Geer moraines)
� Land uplift map in 1888/90� Last glaciation was not longer
than ~9000 years ago
http://eos.tufts.edu/varves/images/varve_chron1.jpg
![Page 41: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/41.jpg)
Postglacial land uplift
de Geer (1888)de Geer (1890)
![Page 42: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/42.jpg)
Remaining question (for now)Questions:�Did sea level fall or did land rise?
Land uplift!�What is the cause?
Former glaciation!�Where was/is the land uplift?
Identified in maps and gravity anomalies�When was the glaciation?
Can be calculated from varves�What are the underlying physics?
![Page 43: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/43.jpg)
http://www.eisberg-tauchen.de
![Page 44: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/44.jpg)
Isostatic models of Airy & Pratt
Close (2010)
Airy-Heiskanen model Pratt-Hayford model
Introduced for mountains!
![Page 45: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/45.jpg)
https://upload.wikimedia.org/wikipedia/en/c/c6/Bundesarchiv_Bild_102-09772%2C_Fridjof_Nansen_%28cropped%29.jpg
Fridtjof Nansen (1861–1930)� Isostasy as explanation of
readjustment� But why does it take so much time
for readjustment (we see it today!)?
Nansen (1921)
![Page 46: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/46.jpg)
https://upload.wikimedia.org/wikipedia/en/0/09/RA_Daly.jpg
Reginald A. Daly (1871-1957)� Two rheological earth models,
"punching hypothesis" and "bulge hypothesis“
(Cathles 1975)
![Page 47: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/47.jpg)
Deep Flow (Punch) Channel Flow (Bulge)Hi Visc Lower Mantle
Daly (1934)
Haskell (1935, 1936, 1937)Q�~0.95 x 1021 Pa sPredict uplift remaining ~ 20 m*
Van Bemmelen & Berlage (1935)100 km channel, Q�~1.3 x 1020 Pa sPredict uplift remaining ~210 m*
Vening Meinesz (1937) Q�~3 x 1021 Pa s
Niskanen (1939) Q�~ 3.6 x 1021 Pa sPredict uplift remaining ~200 m*
Gutenberg (1941) Q�~2 x 1021 Pa s Crittenden (1963), McConnell (1968)
Andrews (1968, 1970) Lliboutry (1971), Artyushkov (1971)
Cathles (1971), Parsons (1972) Post & Griggs (1973) nonlinear flow
Peltier (1974) Walcott (1972)
Rebound modeling and viscosity estimates
*Fennoscandia!
![Page 48: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/48.jpg)
� Theory of physics → equations
� Computers and increase in computational power� Dating methods (for fossils, ice cores etc.) → knowledge
of past glaciations and sea levels� Mapping of the oceans → continental drift → convection
� Satellite missions → global gravity models
Development since the 1950s
Kurt Lambeck W. Richard Peltier(http://www.news.utoronto.ca/sites/default/files/Peltier_12_02-27_0.jpg?1364827862)
![Page 49: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/49.jpg)
49
Glacial Isostatic Adjustment
(R. Steffen, 2013)
![Page 50: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/50.jpg)
How many?Causes of Ice Age?
Ice Ages
![Page 51: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/51.jpg)
Ice Ages through Geologic Time:
Last Ice Age started ~2.6 Ma ago when the Himalayas & Andes were pushed up
Gondwanan Ice Age ~ 300 Ma ago when Pangaea was near the south pole
Huronian 2700 -2300 Ma ago
Ordovician Glaciation ~ 450 Ma ago
Neoproterozoic 850 – 630 Ma ago (Snowball Earth?)
![Page 52: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/52.jpg)
Interglacial
Glacial
a. Global climate history during the Pleistocene
b. Late Quaternarysea-level history
Interstadial – minor glacial retreat/warming
Stadial – minor glacial advance/cooling
Spectrum of climatic variation over the past half million years
Climate and sea-level history
![Page 53: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/53.jpg)
At the height of the last Ice Age 20,000 years ago:• Large ice sheets with up to 3 km thickness covered North America,
Greenland, Northern Europe, parts of Asia, Antarctica• Total ice mass ~3x1019 kg• Sea level fell by ~120 meters
geo.de
![Page 54: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/54.jpg)
Milankovitch’s orbital theory
![Page 55: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/55.jpg)
� Changes in Earth’s orbit (Milankovitch)� Changes in solar output (stellar evolution)� Changes in the location and distribution of
continents (plate tectonics) affect wind and ocean currents
� Polar Wander� Eruption of supervolcanoes, meteorite impact� Changes in the concentration of greenhouse
gases in the atmosphere
Causes of palaeoclimate change
![Page 56: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/56.jpg)
Temperature correlates with greenhouse gas concentration
![Page 57: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/57.jpg)
57
Ice model examples, thickness ca. 18,000 a ago
![Page 58: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/58.jpg)
Ice model for EGSIEM: Ice thickness at 22 ka BP
![Page 59: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/59.jpg)
Deformation & stress of a viscoelastic Maxwell Earth
+Sea-level equation
+Earth rotation
and feedback to sea levels
Physics of GIA
![Page 60: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/60.jpg)
after Ranalli (1995)
Viscoelastic Maxwell Rheology
![Page 61: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/61.jpg)
Shearer (1999) based on PREM (Dziewonski & Anderson 1981)Stein & Wysession (2003)
Determining Earth’s Elastic Structure
![Page 62: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/62.jpg)
Two most common approaches:
1. Laboratory deformation experiments on Earth materials athigh temperatures and pressures. Primary limitations aresimulating realistic strain rates and finding suitablesamples for the deep mantle
2. Geophysical modelling of surface observables related toisostatic adjustment and mantle flow. Primary limitationsare resolving power of data and limitations of models
Determining Earth’s Viscosity Structure
![Page 63: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/63.jpg)
Morelli and Danesi (2004)
Lateral Earth Structure
![Page 64: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/64.jpg)
� � 011 �������� IUUUW&&&&oooo r̂gr̂gu
� �ruu r ˆ001 UwUU ����� &&&
112 4 USI G �
��
wtW wtW0
�PQ
W � 3 I§�©�¨�
·�¹�¸�
��
W0
OT I � 2PH
Div of stress Advection of Prestress
Internal buoyancy
Incremental gravity
Mass Conservation
Newton’s Law:
Self Gravitation
Visco-elastic Maxwell
Volume change
Densitystratification
Perturbeddensity
Perturbed Grav. Potential generated by perturbed density
Elastic & Viscous contribution
Equations to model Earth deformation
![Page 65: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/65.jpg)
After deglaciation,where in the oceans will the melted ice-water go?
Answer: melted ice water will NOT be uniformlydistributed in the oceans!
The Sea-Level Equation
![Page 66: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/66.jpg)
ICE ICE
WATER OCEAN
V (t)S(t)=A
UU� '
'
Glacio-Eustasy
![Page 67: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/67.jpg)
Ice melt
ICE
ICE
OCEAN
OCEAN
Tamisiea et al. (2003)
Perturbations to ocean floor and surface
![Page 68: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/68.jpg)
“mean” sea level is an equipotential surface
Sea-level equation
![Page 69: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/69.jpg)
��
S T,\, t� � I T,\, t� �g
�U T,\, t� �� MI (t)UwAo
�1Ao
I T,\, t� �g
�U T,\, t� �o
ª�
¬�«�«�
º�
¼�»�»�O T,\, t� �
Perturbed Potential:
Radial Displacement:��
I(T,\, t) IL(T,\, t)�IR(T,\, t)
��
U(T,\, t) UL(T,\, t)�UR(T,\, t)
Surface loading Earth Rotation
Sea-level equation with rotational feedback
![Page 70: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/70.jpg)
Effect of rotation on sea-level rate
(Peltier 2007)
![Page 71: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/71.jpg)
Earth Forcing Earth Model
Ice Model� Multidisciplinary approach
Ocean Model� Sea-level equation
Rotational potential� Euler equations
Surface loading Geometry Rheology� Spherical/Flat
� Internal structure: 1D & 3D
� Viscoelastic
� Linear and non-linear viscous deformation
Key elements of a GIA model
![Page 72: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/72.jpg)
72
Earth models3D flat model
130000 km 130000 km
2886
kmCrust
Upper Mantle
Frame
Center
Lower Mantle
3D sphericalFE model
1D model
(Wu 2004, GJI)
(Wu 2004, GJI)3D sphericalFV model
(Latychev et al. 2005, GJI)
(Munk & MacDonald 1960;Farrell and Clark 1976;Mitrovica et al. 1994, JGR;Mitrovica and Milne 1998;Kaufmann et al. 2002, JGRSpada et al. 2007)
Benchmark study bySpada et al. (2010, GJI)
![Page 73: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/73.jpg)
� Geomorphology� Glaciology� Oceanography� Climatology� Rock Physics� Geodynamics� Geodesy � Aerospace Engineering� Astronomy� Archeology
Study of Glacial Isostatic Adjustment is multi-disciplinary!
![Page 74: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/74.jpg)
� Mantle rheology & viscosity profile� Ice thickness & topography model� Geodetic Reference Frame definition� Earth rotation (polar wander, length of day, J-dot)� Monitor Global Warming & Climate Change� Archeology & land boundaries� Geomorphology of the past & future of Water Resources� GIA-induced earthquakes & Nuclear Waste Management� Cause of seismic tomography & lateral heterogeneity � Sensitivity kernel and design of geodetic observation
networks
Recent applications:
![Page 75: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/75.jpg)
Application: water resources, land claim, archaeology, human history
Geomorphology of the past & future
![Page 76: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/76.jpg)
During the last glacial maximum, global sea level dropped by~120 m, exposing continental shelves & forming land bridges.
Sea-level drop allowed human migration from Asia to the Americas during glacial maximum.
Ocean currents no longer warm high latitude area
Effects of LGM
![Page 77: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/77.jpg)
Topographic changes
RF3b ICE-4G
![Page 78: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/78.jpg)
Freshwater seals – trapped after an ice ageBaikal seal Caspian seal
Saimaa ringed seal Ladoga seal
(Source:https://upload.wikimedia.org/wikipedia/commons/d/db/Caspian_Seal.jpg)
(Source:https://upload.wikimedia.org/wikipedia/commons/a/a7/Baikal-seal_4747-pho.jpg)
(Source:https://upload.wikimedia.org/wikipedia/commons/b/b3/The_freshwater_ringed_seals._lake_Ladoga.jpg)
(Source:http://www.sll.fi/mita-me-teemme/lajit/saimaannorppa/ringed-seal/leadImage)
![Page 79: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/79.jpg)
Topographic changes
RF3b ICE-4G
No global warming assumed
![Page 80: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/80.jpg)
Glacial isostatic adjustmentPart 2 - Observations
EGSIEM Summer SchoolPotsdam, Germany13/09/2017
Holger Steffen
With input from Martin Lidberg, Rebekka Steffen, Wouter van der Wal, Pippa Whitehouse and Patrick Wu
![Page 81: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/81.jpg)
What type?Which time period is covered?
GIA Observations
![Page 82: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/82.jpg)
3
Vertical motion Relative sea levels (geologic, palaeontological and
archaeological evidence) Present-day rate of uplift – Levelling, GNSS, tide gauges,
altimetry Horizontal motion - GNSS, VLBI, DORIS Gravity change due to redistribution of mass – terrestrial
(gravimeter) and space-geodetic techniques (GRACE, hlSST) Changes in the state of stress - earthquakes Change in Moments of Inertia Polar wander Non-tidal acceleration (Length Of Day)
Observations of GIA
![Page 83: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/83.jpg)
Glacial Rebound
1
![Page 84: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/84.jpg)
NW Latvia
![Page 85: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/85.jpg)
Relative sea levels in Hudson Bay
RelaxationTime ~ 3.5 ka
Raised beaches
![Page 86: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/86.jpg)
Observed sea-level response to past ice change reflects contributions
These processes will govern the sea-level response to future ice mass change
Australia
New Zealand
Milne et al. (2009)
1
32
![Page 87: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/87.jpg)
Basal peat as sea-level indicator
Vink et al. (2013)
![Page 88: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/88.jpg)
Sea level indicator vs. type of coast
(slides courtesy of Annemiek Vink)
MSL… mean sea levelMHW…mean high water
![Page 89: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/89.jpg)
Photo: H.Lübke
In 7 m water depth
Mesolithic find spot in Poel (southern Baltic Sea)
![Page 90: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/90.jpg)
Photo: H.Lübke
In 3 m water depth
Mesolithic find spot in Timmendorf (Poel)
![Page 91: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/91.jpg)
2,0 to 1,7m below sea level,3 dugout canoes, 6000 – 5000 BP (4900 - 3800 BC)
Find spot 225 in Stralsund
(Picture courtesy of R. Lampe)
![Page 92: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/92.jpg)
Oak stump inGreifswalder Bodden-0,75m HN, 1190 ± 45 BP(840 ± 60 AD)
Recent midwater
(Photo courtesy of R. Lampe)
![Page 93: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/93.jpg)
Whale bones in SW Sweden
(Anderung et al. 2013)
![Page 94: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/94.jpg)
Southern North Sea coast – forebulgeWest Swedish coast - archeology
Example: RSL application in Europe
![Page 95: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/95.jpg)
Postglacial crustal movement
? ? ? ?
Coastal change at the German North Sea coast
(Vink et al., in prep.after Mörner 1980)
Affected by subsidence due to GIA
![Page 96: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/96.jpg)
Relative sea-level data
(Vink et al., in prep.)
![Page 97: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/97.jpg)
Comparison of sea-level curves
(Vink et al. 2007, QSR)
![Page 98: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/98.jpg)
Comparison of sea-level curves
(Vink et al. 2007, QSR)
~15 m
![Page 99: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/99.jpg)
Relative crustal movements
(Vink et al. 2007, QSR)
Generally composed of a local/regional (linear) tectonic component and an (non-linear) isostatic component.
![Page 100: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/100.jpg)
Modelled sea-level curves
(Vink et al., in prep.)
10 8 6 4 2 0Cal kyr BP
![Page 101: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/101.jpg)
Modelled curves vs. sea-level data
(Vink et al. 2007, QSR)
Sea-level curve from the best model of the region
![Page 102: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/102.jpg)
Coastal change at the German North Sea coast
(Vink et al., in prep., after Mörner 1980)
![Page 103: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/103.jpg)
Archeology: The first Swedes
![Page 104: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/104.jpg)
Palaeotopography of the North Sea
(Schmitt 1994, OJOA)
![Page 105: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/105.jpg)
Schmitt et al., AKGG2008, Hirschegg
Hensbacka
Ahrensburg culture
Bromme
![Page 106: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/106.jpg)
Nösund
![Page 107: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/107.jpg)
Swedish coast near Smögen
![Page 108: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/108.jpg)
A Nösund
B Kolamossen
C Gullmarsskogen
(Schmitt et al. 2009, OJOA)
Hensbacka sites
![Page 109: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/109.jpg)
A Nösund10280±100 a BP56 - 57 m a.s.l.
B Kolamossen10260±120 a BP50 m a.s.l.
(Svedhage 1985a,b;Svedhage & Schmitt 1995)
Hensbacka sites
(Schmitt et al. 2009, OJOA)
![Page 110: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/110.jpg)
A Nösund10280±100 a BP56 - 57 m a.s.l.
B Kolamossen10260±120 a BP50 m a.s.l.
C Gullmarsskogen??? a BP65 m a.s.l.
Hensbacka sites
?
(Schmitt et al. 2009, OJOA)
![Page 111: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/111.jpg)
?
Results
a
65 m Gullmarsskogen
(Schmitt et al. 2009, OJOA)
![Page 112: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/112.jpg)
Geodetic techniquesLevelling
GNSSVLBI
Tide gaugesSatellite altimetry
![Page 113: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/113.jpg)
(Repeated) Levelling
(Source:http://www.fig.net/organisation/comm/5/activities/reports/gavle/Image11.gif)
Motorized levelling (introduced by Lantmäteriet in the 70s)
(Source:http://www.fig.net/organisation/comm/5/activities/reports/gavle/Image14.gif)
(Somewhere near the Arctic circle)
![Page 114: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/114.jpg)
Uplift rate mainly from levelling
(after Steffen and Wu 2011)
Apparent uplift!One of the few maps
covering whole northern EuropeMore maps/models
mainly focus on a certain country
![Page 115: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/115.jpg)
Global Navigation Satellite SystemGPS
Measured distance
IonosphereTroposphere
Satellite errorReceiver errorCorrection
Correct distance
GALILEOGLONASS
![Page 116: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/116.jpg)
Permanent GPS systems across Norway, Sweden, and Finland
First observations 1993 Started with 16 sites, quickly
increased to about 40 sites, ~100–200 km spacing
First 3-D map of GIA (anywhere) produced 2001
Published velocity results:2002 Johansson et al., JGR
GIPSY, Aug 1993 - May 2000
2007 Lidberg et al., J GeodesyGAMIT, 1996 - June 2004
2010 Lidberg et al., J GeodynamicsGAMIT, 1996 - fall 2006
BIFROST Project - GNSS
![Page 117: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/117.jpg)
GPS determined uplift rate in Fennoscandia
Data from Scherneck et al. (1998)
(Steffen and Wu 2011)
![Page 118: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/118.jpg)
GPS determined uplift rate in Fennoscandia
Data from Johansson et al. (2002)
(Steffen and Wu 2011)
![Page 119: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/119.jpg)
GPS determined uplift rate in Fennoscandia
Data from Lidberg et al. (2007)
(Steffen and Wu 2011)
![Page 120: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/120.jpg)
GPS determined uplift rate in Fennoscandia
Data from Lidberg et al. (2010)
(Steffen and Wu 2011)
![Page 121: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/121.jpg)
GPS determined uplift rate in Fennoscandia
Two antennas in Arjeplog
![Page 122: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/122.jpg)
43
Observations: BIFROST GNSS data
(Kierulf et al., in prep.)
![Page 123: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/123.jpg)
Fennoscandia
GPS stations and determined uplift velocity in Canada and northern Europe
Canada
Data courtesy of Jim Rohde Data from Lidberg et al. (2007)
Mean time span ~5 yr Mean time span ~8 yr
(Wu et al. 2010, GJI)
![Page 124: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/124.jpg)
Accuracy of GPS observations
Accuracy depends on thetime span of allinstruments in a network,
A longer time spangenerally decreases theerrors.
Calais et al. (2006)
5 years: 0.6 mm/a for tangential velocities2.0 mm/a for vertical velocities
(Calais et al. 2006), 8 years: 0.2 mm/a for tangential velocities
0.5 mm/a for vertical velocities(Calais et al. 2006, Lidberg et al. 2007).
![Page 125: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/125.jpg)
Velocity field from the most recent BIFROST calculation
Uplift > 1cm/a in the centre(somewhere between thecities of Umeå andSkellefteå), forebulge with 1-2 mm/a in northern Germanyand Poland
Horizontal motion generally2-3 cm/a northeastward
![Page 126: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/126.jpg)
former ice
mass center
During deglaciation, crustal horizontalmotions are radially away from theformer ice mass center, and increase inmagnitude away from the load.
In the forebulge region, motions aretowards the former ice mass center.
Fennoscandia BIFROST [Lidberg et al. (2010)]
motions are ~ 2 mm/yr or less
Horizontal deformation due to GIA
![Page 127: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/127.jpg)
Very Long Baseline Interferometry (VLBI)Onsala Space Observatory
25-m telescope
![Page 128: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/128.jpg)
Very Long Baseline Interferometry (VLBI)
![Page 129: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/129.jpg)
Very Long Baseline Interferometry (VLBI)
(James & Lambert 1993)
GIA model predictions of horizontal velocities
![Page 130: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/130.jpg)
(solid lines - best fits to data, dashed lines- due to GIA only)Annually averaged tide gauge record
(Peltier & Tushingham 1989)
![Page 131: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/131.jpg)
Tide gauge & uplift rate
(Steffen and Wu 2011)
![Page 132: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/132.jpg)
resvartg SSDTUS ������
= error-free tide-gauge ratetgS�
U� = land-uplift rate from GPS (due to GIA & tectonics)
T�
D�= contribution due to thermal expansion
= contribution due to recent deglaciation
= annual & interannual variabilityvarS�
= residual sea-level changeresS�
Tide gauge & uplift rate
![Page 133: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/133.jpg)
Satellite altimetry
![Page 134: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/134.jpg)
driftresalt SSSDTS ������ var
driftalttg SSSU ����
= error free altimetry ratealtS�
= altimetry errordriftS�
Combining altimetry & tide-gauge measurements:
land uplift rate can be obtained :
Satellite altimetry & uplift rate
resvartg SSDTUS ������
![Page 135: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/135.jpg)
Satellite altimetry & uplift rate
(Steffen and Wu 2011)
![Page 136: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/136.jpg)
GravimetryStatic
Time-variableRelative, absolute, super-conducting
![Page 137: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/137.jpg)
GOCO02S gravity field anomalies
(Goiginger et al. 2011)
![Page 138: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/138.jpg)
GIA in the static gravity field
60
Satellite-based gravity field EIGEN-GL04C Spherical harmonics
domain 10-60 degree (300-3000km)
(Figure courtesy of Wouter van der Wal)
![Page 139: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/139.jpg)
(Root et al., 2015)
GIA in the static gravity field
![Page 140: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/140.jpg)
Absolute Gravimeter FG5 & measured rates of change in gravity
(Lambert et al. 2006)
![Page 141: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/141.jpg)
Measured rates of change in gravity
(Lambert et al. 2006)
![Page 142: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/142.jpg)
Absolute gravimetry
Fennoscandia
Vertical gravity rate from gravity measurements in Canada and Fennoscandia
Canada
Absolute and relative gravimetry Absolute gravimetry
![Page 143: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/143.jpg)
Absolute gravity stations in Fennoscandia
(Steffen and Wu 2011)
(Gitlein 2009)
![Page 144: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/144.jpg)
Relative gravity measurements in Fennoscandia
(Steffen and Wu 2011)(Mäkinen et al. 2005)
(Redrawn after Mäkinen et al. 2005)
![Page 145: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/145.jpg)
Two identical space crafts flying about 220 kilometers apart in a polar orbit 500 kilometers above the Earth
Map the Earth's gravity fields by using GPS and microwave ranging system
Study gravity variations due to distribution & flow of masswithin the Earth & surrounding
GRACE:Gravity Recovery And Climate Experiment
![Page 146: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/146.jpg)
68
GRACE observation, trend after post-processing
![Page 147: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/147.jpg)
Fennoscandia
Vertical gravity rate from GRACE in Canada and northern Europe
Canada
GFZ RL05, 335 km Gaussian, d/o 60, 01/2003-02/2013
![Page 148: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/148.jpg)
Determination of 1D Earth structure
Sea-level data:1D Model parameters (Steffen and Kaufmann 2005, GJI):hlith = 120 kmvUM = 4 x 1020 PasvLM = 1023 Pas
GRACE:1D Model parameters (Steffen et al. 2010, GJI):hlith = 160 kmvUM = 4 x 1020 PasvLM = 2 x 1022 Pas
Diamond: best model; Dark gray: σ1; Light gray: σ2
![Page 149: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/149.jpg)
Svendsen (2004)
GRACE observes GIA in the Barents Sea
![Page 150: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/150.jpg)
72Root et al. (GRL, 2015)
GRACE observes GIA in the Barents Sea
![Page 151: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/151.jpg)
Background: water storage from GRACEGRACE
ICE-5G(GIA)
(GIA+Hydro)
GRACE – ICE-5G(Hydro)
(Wang et al. 2013, Nature Geosci.)
Common GIA correction using ICE-5G
![Page 152: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/152.jpg)
CSR GRACE 2003-2011
(Wang et al. 2013, Nature Geosci.)
GPS 1993-2006(Sella et al. 2007)
Hydrological trend in North America
GRACE - ICE-5GGRACE - GPS
GIA correction using GPS-observed GIA
Peak A
![Page 153: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/153.jpg)
Averaged groundwater vs. GRACE
Drought
Flood
(Wang et al. 2013, Nature Geosci.)
![Page 154: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/154.jpg)
Absolute gravity stations in Fennoscandia
FG5-233 from Lantmäteriet(Photo: Steffen)(Steffen et al. 2012, GJI)
Greta
![Page 155: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/155.jpg)
Gravity change gafter Ekman and Mäkinen (1996)
FG5-220 from IfE (Photo: Gitlein) Figure courtesy of O. Gitlein
Absolute gravity network
![Page 156: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/156.jpg)
Comparison to absolute gravity(Steffen et al. 2009b, Tectonophysics)
![Page 157: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/157.jpg)
Combinations
![Page 158: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/158.jpg)
Connection to NAP: In Sweden, forexample, national height systemRH2000 is a realization of the EuropeanVertical Reference System (EVRS)using the Normaal Amsterdams Peil(NAP) as zero level
Common reference epoch: for alllevelling observations
Today’s position: due to land uplift,position as of today is different to theone in the reference system (differentepoch)
Why do we need models of land uplift?1 time2 times3 times≥4 times
(Vestøl, 2016)
![Page 159: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/159.jpg)
Land-uplift map from combined observations
(Steffen and Wu 2011)
Apparent uplift!Combined from repeated
levelling, tide gauges and lake levelsWidely accepted within
the Nordic community
![Page 160: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/160.jpg)
Geodetic observations alone are used to calculate the absolute land uplift inITRF2008
Example NKG2016LU: Trend surface consisting of a 5th degree polynomial; least-squares collocation to estimate an additional signal (=difference from trendsurface); a first order Gauss-Markov covariance function with halved correlationafter 40 km and variance (3 cm/a)2 selected for this latter part of the solution
82
Basic concepts for an empirical model
1 time2 times3 times≥4 times < 0.2 mm/a
< 0.5 mm/a> 0.5 mm/a
Std. dev.
Levelling GNSS Empirical modelSome math
Least-squares collocation with unknown parameters to estimate the absolute uplift in the observation points
+ + =
![Page 161: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/161.jpg)
Absolute land uplift in ITRF2008(relative to the centre of mass)
Statistics:
Should be used for the correctionof GNSS or other space geodetictechniques
# 313 x 301
Min -4.61
Max 10.29
Mean 0.90
StdDev 3.14
83
NKG2016LU_abs
0.5 mm/a contour interval
Residual surface (grid)
grid grid obs. points obs. pointsNKG2016LU_abs NKG2016GIA_prel0306 empirical_abs NKG2016GIA_prel0306h h LSC h h
![Page 162: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/162.jpg)
(Müller et al. 2011, PCE)
Further data combination model examplesGRACE + AG (+ GPS) +
geophysical model
nm/s2/yr
(Hill et al. 2011, JGR)
GRACE + GPS + tide gauges
![Page 163: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/163.jpg)
Application: Nuclear Waste Management
Intraplate Earthquakes and glacially induced faults
![Page 164: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/164.jpg)
(R. Steffen 2013)
Stress due to GIA
![Page 165: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/165.jpg)
BA - Bell Arch; BB - Baffin Bay; BU - Boothia Uplift;GB - Grand Banks; LS - Labrador Sea; OBG - Ottawa Bonnechere Graben. SLV - St. Lawrence Valley;
Most seismic activity in Eastern Canada along the 3 tectonic trends or pre-weakened zones:
1) BB-LS-GB Mesozoic rift margin
2) BU-BA reactivated Paleozoic structures
3) SLV-OBG Paleozoic rifts
Earthquakes in Eastern Canada
(R. Steffen et al. 2012)
![Page 166: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/166.jpg)
Earthquakes in Northern Europe
www.seismo.helsinki.fi
Most seismic activity offshore Norway and Bothnian Gulf (oil and ore extraction)
(update fromSteffen & Wu 2011,J. Geodyn.)
![Page 167: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/167.jpg)
~30cm
Ungava fault(Adams, 1996)
Osning thrust(Brandes et al., 2012)
Pärvie fault (Lagerbäck & Sundh, 2008)
Glacially induced faults
![Page 168: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/168.jpg)
Pärvie fault(Lagerbäck & Sundh, 2008)
~10m
Glacially induced faults
![Page 169: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/169.jpg)
Glacially induced faults in Europe
??
?
!
L: Lansjärv fault
LS: Lainio-Suijavaara fault
P: Pärvie fault
S: Stuoragurra fault
!
Bollnäs fault
Fault in Lake Vättern
Usedom Island
W Poland
Osning Thrust
![Page 170: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/170.jpg)
Fault & focal mechanisms
![Page 171: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/171.jpg)
s
s
t
t t t m so f
t oShear Strength
fm Internal friction
Mechanical strength is controlled by the sliding of one fracture surface on the other - due to the shear stress t. On the other hand, the normal stress s presses the fracture surfaces together, increasing the friction and prevent sliding.
Mohr-Coulomb failure criterion
τ0µf
τσ
s
s
t
t t t m so f
t oShear Strength
fm Internal friction
Mechanical strength is controlled by the sliding of one fracture surface on the other - due to the shear stress t. On the other hand, the normal stress s presses the fracture surfaces together, increasing the friction and prevent sliding.
![Page 172: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/172.jpg)
GIA and stress in a thrust/reverse regime
(R. Steffen et al. 2014)
![Page 173: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/173.jpg)
Change in Coulomb Failure Stress
![Page 174: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/174.jpg)
Change in Coulomb Failure Stress
![Page 175: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/175.jpg)
Change in Coulomb Failure Stress
![Page 176: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/176.jpg)
98
Data summary
Helpful constraint
Today’s accurate snapshotThe reliable past
The blurry future
A model that can describe all that (and more) will provide us the best view into the future!
![Page 177: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/177.jpg)
Changes in Moments of Inertia
![Page 178: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/178.jpg)
GIA causes mass (ice and mantle masses) to redistribute
around the globe, thus disturbs the gravity field
Movement of mass also affect the Moment of Inertia, thus
the rotational motion of the Earth (polar wander and
changes in the Length of Day)
![Page 179: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/179.jpg)
Conservation of Angular Momentum
Length of Day decreases by ~0.7 ms/century
GIA affects Earth’s Rate of Rotation
![Page 180: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/180.jpg)
Source w3/W (10-10/year)Currot (1966) 0.7 + 0.3Muller & Stephenson (1975) 1.5 + 0.3Morrison (1973) 2.9 + 0.6Lambeck (1977) 0.69 + 0.3Stephenson & Morrison (1995) 0.69 + 0.2
.
i.e. Length of Day decrease by ~0.7 ms/century
Wu & Peltier (1984) : Non-tidal acceleration is related to the time rate of change of J2 multiply by the constant
2MERE2
3C
Measurements of non-tidal acceleration
![Page 181: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/181.jpg)
Show Secular (True) Polar Wander (blue lines) superposed on the oscillatorysignal.
The 7 year beat in the signal is a consequence of the superposition of the 12 month forced annual wobble and the 14 month Chandler wobble.
ILS data
![Page 182: Glacial isostatic adjustment - An introductionegsiem.eu/images/static/Autumn-School/Presentations/Steffen.pdf · concept of Glacial-Isostasy, and its Modelling up to 1974 in Dynamics](https://reader031.vdocuments.us/reader031/viewer/2022041517/5e2bd9b164c5fa38a62d6750/html5/thumbnails/182.jpg)
Earth’s spin axis tend to align itself with the axis of greatest moment of inertia
Secular Polar Wander