Abstract
ABSTRACTWe recorded the ice motion and icequakes on the floating part of Langhovde Glacier in East Antarctica to better understand the dynamic behavior of ice shelves and floating tongues. Diurnal and semi-diurnal variations in ice motion and seismicity were simultaneously observed at all four global navigation satellite system and three seismic stations over 2 weeks. The short-term along-flow ice motion is explained by the elastic response of the glacier to ocean tide-induced hydrostatic stress variations, which decayed at a rate of 0.8 km−1 toward the grounding line. We observed a large number of icequakes during mid-rising and high tides that covered a broad frequency range and formed two major groups of events centered at 10 and 120 Hz, respectively. The hourly occurrence rates were ~500 events h−1, with the observed seismicity consistent with fracture due to floating tongue bending. We also observed minor secondary peaks at high ice speeds, which could reflect surface cracking due to stretching or basal friction. Our observation demonstrates that tidal-modulation was the main factor to fracture the floating tongue of Langhovde Glacier.
Highlights
The Antarctic ice sheet is fringed by ice shelves and floating glacier tongues that account for 74% of its coastal margin (Bindschadler and others, 2011)
Similar tide-modulated diurnal and semi-diurnal fluctuations were observed for the vertical motion, but they were an order of magnitude larger than the along-flow motion (Fig. 2c)
The vertical ice motion had an order of magnitude larger tidal admittance than the along-flow motion near the terminus
Summary
The Antarctic ice sheet is fringed by ice shelves and floating glacier tongues that account for 74% of its coastal margin (Bindschadler and others, 2011). Studies on the dynamics of ice shelves and floating ice tongues are crucial to elucidate how changes in stress balance propagate into the Antarctic interior. Previous studies have shown that ocean tides have a strong influence on along-flow and vertical ice-shelf motion (King and others, 2011; Makinson and others, 2012; Robel and others, 2017). It is known that these tide-modulated ice-shelf flow variations influence the basal shear stress at the ice/bed interface of the nearby grounded ice, with this effect propagating many tens of kilometres into the interior from the grounding line (Anandakrishnan and others, 2003; Gudmundsson, 2006). The amplitudes and phases of these variations are different among the Antarctic ice shelves (Makinson and others, 2012; Robel and others, 2017), indicating that complex mechanisms link tide-modulated ice-shelf processes.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
