1. Department of Earth Sciences Dalhousie University Halifax Nova Scotia Canada
2. Now at Shell Canada Energy Calgary Alberta Canada
3. Lamont‐Doherty Earth Observatory Columbia University Palisades New York USA
4. Institut de Physique du Globe de Paris Paris France
5. Woods Hole Oceanographic Institution Woods Hole Massachusetts USA
6. Paradigm Geophysical Ltd Houston Texas USA
7. Now at Absolute Imaging Inc. Calgary Alberta Canada