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IPY-Det internasjonale polaråret 2007/2008

The Dynamic Continental Margin Between the Mid-Atlantic-Ridge System (Mohns Ridge, Knipovich Ridge) and the Bear Island Region

Tildelt: kr 6,0 mill.

A concentrated active and passive seismological experiment along the continental margin of the Barents Sea near Bear Island and the mid-Atlantic along the Knipovich Ridge is proposed. We will study the Earth´s structure and dynamics at this margin from it s top sedimentary cover to its imprint in the upper mantle. The continental margin in this region includes an extremely thick sedimentary wedge and steep slopes, with at least one major paleo fracture-zone cutting through the wedge. Recent studies in this area indicate very low seismic velocities in the lithosphere, which may be explained by a subcrustal extension of Mohns Ridge. The stress field undergoes an extensional-compressional transition in the region of the margin. It is therefore of particular i nterest to understand the structural architecture, the stress and the dynamics of the whole region because of its natural hazard exposure, and the processes involved in formation of the margin and opening of the Atlantic. The collection of deep seismic so unding data, and detailed monitoring and analysis of the seismicity between margin and mid-Atlantic ridge system, using temporary broadband stations, are necessary for providing such information. Data from existing seismic stations in the European Arctic will also be analysed. The planned field experiments comprises installation and parallel operation of seismic instruments during 2007-2008. This includes installation of a small broadband array on Bear Island and 12 broadband Ocean Bottom Seismometers (OB Ss). In addition, we plan to install two broadband stations at the Polish observatory at Hornsund and on Hopen. We also plan to perform active seismic refraction/reflection experiments along two profiles crossing the mid-Atlantic ridge systems, the margin and Bear Island. The profiles will be supplemented with 40 short-period stations on Bear Island and 15 OBSs to retrieve the 3D lithospheric structure.


IPY-Det internasjonale polaråret 2007/2008