Sean Maher, University of California, Santa Barbara, Department of Earth Science, Santa Barbara, CA, United States, Robin S Matoza, University of California, Santa Barbara, Department of Earth Science and Earth Research Institute, Santa Barbara, CA, United States, Catherine D de Groot-Hedlin, University of California San Diego, La Jolla, CA, United States, Arthur D Jolly, GNS Science-Institute of Geological and Nuclear Sciences Ltd, Lower Hutt, New Zealand, Kent Gee, Brigham Young University, Physics, Provo, UT, United States and David Fee, University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK, United States