1. Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography; University of California; San Diego La Jolla California USA
2. Now at Department of Earth Sciences; University of New Hampshire; Durham, New Hampshire USA
3. ETH Zurich, Institute of Geophysics / Schweizer. Erdbebendienst; Sonneggstrasse Zurich Switzerland
4. Now at NORSAR Kjeller; Norway