[1] Univ Colorado, Inst Arctic & Alpine Res, Boulder, CO 80309 USA
[2] Washington State Univ, Dept Geol, Vancouver, WA 98686 USA
[3] Univ Rhode Isl, Grad Sch Oceanog, Narragansett, RI 02882 USA
[4] Princeton Univ, Dept Geosci, Princeton, NJ 08544 USA
[5] Univ Texas, Inst Geophys, Austin, TX 78759 USA
[6] Univ Washington, Geophys Program, Seattle, WA 98195 USA
[7] US Geol Survey, Denver Fed Ctr, Englewood, CO 80225 USA