Tremor and Slow Slip in the West Antarctic Ice Sheet

Bradley P. Lipovsky, & Eric M. Dunham

Submitted August 15, 2016, SCEC Contribution #6838, 2016 SCEC Annual Meeting Poster #072

The Whillans Ice Plain region of the West Antarctic Ice Sheet experiences twice-daily, tidally-modulated slow slip events. During each event, 0.5 m of slip occurs over a 150x150 km area. Sliding initiates at one of several recurring locations and expands outwards with a typical rupture velocity ~200 m/s. In addition, slow slip events are accompanied by seismic tremor episodes. Understanding the mechanical processes that gives rise to these curious phenomena has implications for both sea level rise hazard and for our knowledge of faulting processes more generally.

We model these observations using a simplified model that includes the effects of inertia, elasticity, tidal forcing, and rate- and state-dependent frictional sliding. We interpret seismic tremor during slow slip events as due to the failure of m-scale rate weakening patches at the ice-bed interface. We find that, at the ~km-scale, slow rupture velocities are explained by basal conditions that are near the steady sliding limit. Such conditions arise in our simulations due to the presence of high pore pressures such that the subglacial effective normal stress is ~10 kPa where the ice overburden pressure is 7.2 MPa.

Key Words
Tremor, Slow Slip, Antarctica, Glaciology

Lipovsky, B. P., & Dunham, E. M. (2016, 08). Tremor and Slow Slip in the West Antarctic Ice Sheet. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)