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IAG Commission 3: Earth Rotation and Geodynamics
Sub-Commission 3.2: Crustal Deformation.
Chair: Markku Poutanen
Directing Board
M. Poutanen (Chair), J. Davis, K. Heki, S. Zerbini, J. Manning, J. Sledzinski
Terms of Reference
There are many geodetic signals that can be observed and are representative of the deformation mechanisms of the Earth's crust at different spatial and temporal scales. The time scales range from seconds to millions of years in the case of plate tectonics and from millimeters to continental dimension for the spatial scales.
Space geodetic measurements provide nowadays the means to observe deformation and movements of the Earth's crust at global, regional and local scales. This is a considerable contribution to global geodynamics by supplying primary constraints for modeling the planet as a whole, but also for understanding geophysical phenomena occurring at smaller scales.
Gravimetry, absolute, relative and nowadays also spaceborn, is a powerful tool providing information to the global terrestrial gravity field and its temporal variations. Superconducting gravimeters allow a continuous acquisition of the gravity signal at a given site with a precision of 10-10. This is important in order to be able to detect and model environmental perturbing effects as well as the weak gravity signals associated with vertical crustal movements of the order of mm/yr. These geodetic observations together with other geophysical and geological sources of information provide the means to understanding the structure, dynamics and evolution of the Earth system.
Objectives
General objectives of the Sub-Commission 3.2 will include:
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to study tectonic motions, including plate deformation;
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to study postglacial rebound, but also glacial dynamics and glacial isostatic adjustment in the currently glaciated area of the Earth, as well as the water and ice mass balance;
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to study local crustal movements, some of which could be potentially hazardous;
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to study sea-level fluctuations and changes in relation to vertical tectonics along many parts of the coastlines and in relation to environmental fluctuations/changes affecting the geodetic observations;
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to promote, develop and coordinate international programs related to observations, analysis and data interpretation for the three fields of investigation mentioned above;
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to promote the development of appropriate models.
There are particular objectives for the different entities, in the frame of the general objectives.
One should also notice, that the objectives of the integrated global geodetic observing system (IGGOS) includes e.g.
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the integral effect on Earth rotation of all angular momentum exchange inside the Earth, between land, ice, hydrosphere and atmosphere, and between the Earth, Sun, Moon, and planets,
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the geometric shape of the Earth's surface (solid earth, ice and oceans), globally or regionally, and its temporal variations, whether they are horizontal or vertical, secular, periodical or sudden, and
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by adding the Earth's gravity field-stationary and time-variable-mass balance, fluxes and circulation.
According to these objectives, SC3.2 should have close contacts to the IGGOS activities, because many of the items are shared in the plans of IGGOS and SC3.2.
Structure and forms of activities
The Sub-Commission on Crustal Deformation comprises sub-entities or working groups corresponding either to different geographical regions or different important and actual topics involved in the field of the Sub-Commission studies. These sub-entities are dealing with main scientific objectives having common general aspects and, in parallel to these objectives, follow the development of technology and measurement techniques capable to best fulfill the scientific objectives.
The SC3.2 will promote itself, but also encourage its working groups and other related groups or institutions to organize meetings or larger scientific conferences for selected scientific or technological subjects. Outcome of these meetings will be published in Proceedings, either separate one or as special issues of scientific journals.
Sub-entities or working groups will be established by the directing board according to the needs or activities. This list will be completed later, and more groups are to be added. Currently, the following group exists
Related Working Groups
“Working group of European Geoscientists for the Establishment of Networks for Earth science Research (WEGENER)”, chaired by L. Bastos, and earlier being as a sub-entity of Commission XIV is now a separate group. However, close contacts between WEGENER and SC3.2 will be continued.
Own website: http://iagsc32.fgi.fi/
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