1. Consulting Geologist, c/o US Geological Survey, 345 Middlefield Road (M.S. 969), Menlo Park, CA 94025, United States
2. US Geological Survey, 345 Middlefield Road (M.S. 999), Menlo Park, CA 94025, United States
3. Naval Research Laboratory, Washington, DC, United States
4. Present address: National Geodetic Survey (N/NGS4), 1315 East-West Highway, Silver Spring, MD 20910, United States