Projet ANR-15-CE31-0015 – AlpArray-FR : Voir et comprendre les Alpes en 3D, de la croûte au manteau
Programme : Défi de tous les savoirs (DS10) 2015
Année de financement : 2015
Coordinateur du projet : Madame Anne Paul (Institut des Sciences de la Terre)
Montant : 620000.0 euros
Date de début : 2015
Durée : 48 mois
Résumé : Millions of Europeans live on land formed by the Alpine orogeny and are affected by its topography, geology and associated natural hazards. The Alps have been intensely studied by geologists for more than a century, and they provide a unique natural laboratory to advance our understanding of orogenesis and its relationship to present and past mantle dynamics. While most concepts that underlie current studies of mountain belts and convergence dynamics were born in the Alps, this belt has not been given the attention it deserves using recent geophysical techniques. The ambition of the European AlpArray collaborative project is to re-evaluate the deep structures and processes that occur beneath the Alps by exploiting cutting-edge developments in geophysical imaging. AlpArray will provide unified and homogeneous seismological land-sea coverage of the greater Alpine area at an unprecedented scale and station density within Europe (~40 km average station spacing). AlpArray is timely, feasible and practically possible, as the scientific and technical obstacles have now all been overcome. The number of permanent seismic stations has risen significantly over the last decade, making the dense backbone with the number of available mobile broadband seismic pools feasible. The distributed European data distribution system EIDA is now operational and efficient. Finally, the seismological high-resolution imaging methods are not only available, but also practically feasible through the increase in computational capacity. With all these elements assembled, the enthusiasm for joining forces to install and operate AlpArray has been immediate across all of the ~15 countries involved.
The AlpArray-FR project is the French component of AlpArray. The French team will deploy and operate a temporary network of 80 land and 9 seafloor seismometers, located in Eastern France and the Mediterranean, in total providing more than 20% of the total data collected by AlpArray. In addition to participating in the collective research effort on the entire Alpine region, the AlpArray-FR team will focus particularly on the westernmost part of the Alps and adjoining areas, with special interest in the junction and interaction between the Alps and the Apennines – hence the inclusion of sea based observations in the Ligurian Sea. Despite negligible present-day horizontal shortening, the Western Alps and their junction with the Mediterranean Sea are among the most seismically active areas in Western Europe. AlpArray will improve the threshold of detection of this enigmatic seismicity at the scale of the Western Alps and their forelands including the highly populated Alpine valleys, the Rhône valley and the Mediterranean border. A third area of research is focussed on developing and adapting new methods of seismic imaging to the particularly complex and challenging target of the Alpine lithosphere-asthenosphere system, ranging from exploring the limits of seismic noise correlation techniques, and the combined inversion of complementary geophysical observables (e.g. seismic and gravity data) to full-waveform inversion.
Funding has already been secured in most partner countries and funding of this project by ANR this year would put the whole AlpArray project in a safer position. All equipment necessary for AlpArray-FR is already available through the national research facility RESIF (associated with the RESIF national investment project, ‘PIA EquipEx’). AlpArray-FR is moreover an excellent opportunity to add scientific value to RESIF. The dense seismic profiles necessary for the calibration of the 3D images are operated through a Chinese-French-Italian cooperation. AlpArray-FR includes 3 partners in charge of field operations and research, and 5 additional research partners. The research activities will take place during and for at least 5 years after the end of the present project and will be largely funded through other national, regional and local sources.