1. Deschutes Signal Processing LLC, Maupin, Oregon, USA..
2. Formerly NORSAR, Kjeller, Norway; presently University of Franche-Comté, Lab. Chrono-environnement, Besançon, France..
3. NORSAR, Kjeller, Norway..
4. NORSAR, Kjeller, Norway and GFZ German Research Centre for Geosciences, Potsdam, Germany..
5. The University Centre in Svalbard, CO2 Lab, Longyearbyen, Norway..