02073nas a2200265   4500008004100000022001400041245008200055210006900137260000800206300001400214490000700228520122600235653001801461653002301479653004201502653001301544653001501557100002401572700002001596700002001616700002301636700002401659700002801683856009601711       2018                        eng d  a0022-143000aActive seismic studies in valley glacier settings: strategies and limitations0 aActive seismic studies in valley glacier settings strategies and  coct  a796–8100 v643 aSubglacial tills play an important role in glacier dynamics but are difficult to characterize in situ. Amplitude Variation with Angle (AVA) analysis of seismic reflection data can distinguish between stiff tills and deformable tills. However, AVA analysis in mountain glacier environments can be problematic: reflections can be obscured by Rayleigh wave energy scattered from crevasses, and complex basal topography can impede the location of reflection points in 2-D acquisitions. We use a forward model to produce challenging synthetic seismic records in order to test the efficacy of AVA in crevassed and geometrically complex environments. We find that we can distinguish subglacial till types in moderately crevassed environments, where ‘moderate' depends on crevasse spacing and orientation. The forward model serves as a planning tool, as it can predict AVA success or failure based on characteristics of the study glacier. Applying lessons from the forward model, we perform AVA on a seismic dataset collected from Taku Glacier in Southeast Alaska in March 2016. Taku Glacier is a valley glacier thought to overlay thick sediment deposits. A near-offset polarity reversal confirms that the tills are deformable.10aglacial tills10aglacier geophysics10aglaciological instruments and methods10aseismics10asubglacial1 aZECHMANN, JENNA, M.1 aBOOTH, ADAM, D.1 aTruffer, Martin1 aGusmeroli, Alessio1 aAmundson, Jason, M.1 aLarsen, Christopher, F.  uhttps://www.cambridge.org/core/product/identifier/S0022143018000692/type/journal{\_}article01966nas a2200241   4500008004100000022001400041245010500055210006900160300001000229520113200239653001701371653002301388653004201411100002001453700002301473700002301496700001901519700001901538700002501557700002001582700002601602856009601628       2017                        eng d  a0022-143000aAcquisition of a 3 min, two-dimensional glacier velocity field with terrestrial radar interferometry0 aAcquisition of a 3 min twodimensional glacier velocity field wit  a1–83 a{\textless}p{\textgreater}Outlet glaciers undergo rapid spatial and temporal changes in flow velocity during calving events. Observing such changes requires both high temporal and high spatial resolution methods, something now possible with terrestrial radar interferometry. While a single such radar provides line-of-sight velocity, two radars define both components of the horizontal flow field. To assess the feasibility of obtaining the two-dimensional (2-D) flow field, we deployed two terrestrial radar interferometers at Jakobshavn Isbrae, a major outlet glacier on Greenland's west coast, in the summer of 2012. Here, we develop and demonstrate a method to combine the line-of-sight velocity data from two synchronized radars to produce a 2-D velocity field from a single (3 min) interferogram. Results are compared with the more traditional feature-tracking data obtained from the same radar, averaged over a longer period. We demonstrate the potential and limitations of this new dual-radar approach for obtaining high spatial and temporal resolution 2-D velocity fields at outlet glaciers.{\textless}/p{\textgreater}10aglacier flow10aglacier geophysics10aglaciological instruments and methods1 aVoytenko, Denis1 aDixon, Timothy, H.1 aHolland, David, M.1 aCassotto, Ryan1 aHowat, Ian, M.1 aFahnestock, Mark, A.1 aTruffer, Martin1 aDe La Peña, Santiago  uhttps://www.cambridge.org/core/product/identifier/S0022143017000284/type/journal{\_}article