Simulations of flexural-gravity wave response of Antarctic ice shelves to tsunami and ocean wave impacts
- Floating ice shelves off the coast of Antarctica play an important role in buttressing the outflow of grounded ice. These ice shelves are subject to the continuous impact of ocean waves and tides which can induce their flexure, create bending stresses, and possibly facilitate rifting and calving. Ice shelves have complex geometries and spatially variable ice thickness and water depth. These features that are challenging or impossible to capture with the commonly used semi-analytical methods that have been used to study wave reflection, transmission, and propagation. In this thesis, we will address this challenge, firstly, by introducing a provably stable, higher-order-accurate finite difference method to solve the 2D (map view) problem of an incompressible ocean partially covered with an elastic plate. The method is based on the summation-by-parts--simultaneous approximation terms (SBP-SAT) framework, and uses curvilinear multiblock grids to handle complex geometries. The model solves the Euler-Bernoulli plate equation, with spatially variable properties, coupled with the 2D variable depth shallow water equations. We demonstrate the stability and accuracy of the numerical model using the method of manufactured solutions. Next, we apply the new method to study ocean wave forcing of the Thwaites Glacier Ice Tongue, Eastern Ice Shelf and Pine Island Ice Shelf, with ice thickness and water depth from BedMachine2. We also apply our model to Ross Ice Shelf, where seismic data exists for validation. We reproduce observed attenuation of waves in the infragravity band (IG, 0.003-0.03 Hz) and the absence of attenuation in the very long period band (VLP, less than 0.003 Hz). This attenuation is attributed to scattering losses that are captured by our model. Finally, we model the response of these ice shelves to tsunamis from the 2015 Mw 8.3 Illapel, Chile, earthquake and to a hypothetical Mw 8.6 earthquake in the Central American subduction zone. We calculate maximum wave amplitudes and bending stresses, in particular identifying regions that experience large bending stresses from wave focusing and amplification. One such region is on the upstream side of the pinning point of the Thwaites Eastern Ice shelf, a location of critical importance for the stability of the West Antarctic Ice Sheet.
|Type of resource
|electronic resource; remote; computer; online resource
|1 online resource.
|Degree committee member
|Degree committee member
|Stanford University, Institute for Computational and Mathematical Engineering
|Statement of responsibility
|Submitted to the Institute for Computational and Mathematical Engineering.
|Thesis Ph.D. Stanford University 2022.
- © 2022 by Nurbek Tazhimbetov
- This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).
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