1. Large Lakes Observatory; University of Minnesota; Duluth Minnesota 55812 USA
2. Universitåt Bern; Institut für Geologie; CH-3012 Bern, Erlachstrasse 9a Switzerland
3. Global Undersea Research Unit; P.O. Box 475, Moss Landing California 95039 USA
4. University of Southern California; Department of Earth Sciences; Los Angeles California 90089 USA