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A new network of GPS stations to measure movement of the earth’s crust

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05.04.2007

This new cross-border network is the first of its kind and was devised to determine the changes in the earth’s crust that are the source of earthquakes and that form the Alpine region’s relief. This system is comprised of 40 fixed high-resolution, continual recording GPS (1) stations. With submillimetric precision (2), the network will also be highly useful for all professionals who work with GPS.

One aim of this project is to increase understanding of seismic risks throughout the Alpine chain and the surrounding regions. Urban zones in full development, as well as some major European centres (Grenoble, Geneva, Torino,…), are concentrated along the mountain chain. Thanks to this new network of GPS stations, it will be possible to continuously measure slow (3) and low amplitude movements in the earth’s crust with great precision. The information provided by the network, added to geologic data on of the fault zones, will contribute to a better localisation of potential seismic sites, their size and their consequences in terms of expected damages in the Alpine region.

The project, begun three years ago, was implemented by 12 partners, including 2 in France: the Laboratory of Internal Geophysics and Tectonophysics (4) at the University Joseph Fournier in Grenoble and the Strasbourg Institute of Earth Physics (5) (IPGS) at the University Louis Pasteur (ULP) in Strasbourg. The IPGS brought its expertise in characterising active faults for seismic risk and measuring deformations with high precision spatial geodetics (6) (GPS).

Of the 40 stations located in the Alpine region, 5 have been acquired by the IPGS thanks to co-funding from the Région Alsace, the CNRS and the European programme Interreg III B – Alpine region. These 5 stations are installed in Alsace on geological sites that meet the specific criteria necessary for such high precision. They complement the 2 existing stations, STJ9 and WELS (7) of ULP’s Earth science Engineering School and Observatory (EOST).

In Alsace, the new GPS network will also be very useful for all potential users of geodesic data on local communities. Cadastral services (property management), surveyors (urban planning, regional development), network managers (water, gas, and telecommunications), cartographers, civil security services, as well as agriculture (land plotting), navigation, transportation, and meteorological services will all find the information highly useful.

1) GPS (Global positioning system) : Geodesic spatial system, that allows three-dimensional positioning (latitude, longtitude, altitude) as well as measurement of time. It has been operational since 1994 ; with 24 satellites, it guarantees full coverage of the globe 24 hours a day.

2) Submillimetric precision: positioning under one millimetre.

3) Slow movements: “slow“ movement is more difficult to study than the “rapid“ movement typical of tectonic regions such as the San Andreas Fault (California) or the Anatolian Fault in Turkey.

4) Joint research unit CNRS/UJF, UMR 5559.

5) Joint research unit CNRS/ULP, UMR 7516.

6) Geodetics: the science that studies the form and dimensions of the earth.

7) STJ9 and WELS: These two stations are part of the observational network of the EOST. STJ9 benefits from support from the Région Alsace. These stations are part of France’s national GPS network (RENAG) of the National Institute for the Sciences of the Universe (CNRS) and the French GPS permanent network (RGP).

Research Contact:
Dr. Jerome van der Woerd
Tél. 03 90 24 03 49
jeromev@eost.u-strasbg.fr

Isabel Pellon Zarragoitia | Source: alphagalileo
Further information: www.u-strasbg.fr

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