1. U.S. Geological Survey; Denver Federal Center; MS 973,; Denver; Colorado; 80225; USA
2. Department of Geosciences; Oregon State University; 104 Wilkinson Hall,; Corvallis; Oregon; 97330-5506; USA
3. College of Oceanic and Atmospheric Sciences; Oregon State University; 104 COAS Admin Bldg.,; Corvallis; Oregon; 97333-5503; USA