Robert A Zierenberg, University of California Davis, Earth and Planetary Sciences, Davis, CA, United States, Gudmundur Ómar Fridleifsson, HS Orka hf, Reykjanesbæ, Iceland, Wilfred A Elders, University of California, Earth Sciences, Riverside, CA, United States, Peter Schiffman, Univ California, Davis, CA, United States, Andrew P Fowler, University of California Davis, Davis, CA, United States and Mark H Reed, Univ Oregon, Eugene, OR, United States