1. U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado 80303, United States
2. U.S. Geological Survey, 1730 East Parham Road, Richmond, Virginia 23228, United States
3. University of Colorado Denver, 1151 Arapahoe Street, SI 2071, Denver, Colorado 80204, United States
4. U.S. Geological Survey, 6000 J Street, Placer Hall, Sacramento, California 95819, United States
5. U.S. Geological Survey, 400 South Clinton Street, Iowa City, Iowa 52240, United States
6. U.S. Geological Survey, 4821 Quail Crest Place, Lawrence, Kansas 66049, United States