1. U.S. Geological Survey, Columbia, South Carolina 29210, United States
2. U.S. Geological Survey, Columbus, Ohio 43229, United States
3. U.S. Geological Survey, Lawrence, Kansas 66049, United States
4. U.S. Geological Survey, Austin, Texas 78754, United States
5. U.S. Geological Survey, Sacramento, California 95819, United States
6. U.S. Geological Survey, Beaverton, Oregon 97201, United States
7. U.S. Geological Survey, Portland, Oregon 97201, United States