Earth & Space Research, 1910 Fairview Ave. E., Suite 102, Seattle, WA 98102-3620 United States
School of Civil Engineering and Geosciences, University of Newcastle, Newcastle Upon Tyne, NE1 7RU United Kingdom
Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanograpy University of California, San Diego 9500 Gilman Drive, La Jolla, CA 92093-0225 United States