1. Norwegian Polar Research Institute, P. 0. Box 158, 1330 Oslo Lufthavn, Norway;
2. Norwegian Petroleum Directorate, P. 0. Box 600, N-4001 Stavanger, Norway;
3. Elf Aquitaine Norge A/S, P.O. Box 168. N-4001 Stavanger, Norway; April 1983 (revised July 1983).