Evolution of shear-zone fractures presages the disintegration of Thwaites Eastern Ice Shelf
| dc.contributor.author | Banerjee, Debangshu | |
| dc.contributor.examiningcommittee | Siegfried, Matthew (Colorado School of Mines) | |
| dc.contributor.examiningcommittee | Kuzyk, Zou Zou (Earth Sciences) | |
| dc.contributor.supervisor | Alley, Karen | |
| dc.contributor.supervisor | Dahl-Jensen, Dorthe | |
| dc.date.accessioned | 2024-08-29T17:14:49Z | |
| dc.date.available | 2024-08-29T17:14:49Z | |
| dc.date.issued | 2024-08-26 | |
| dc.date.submitted | 2024-08-26T06:00:53Z | en_US |
| dc.degree.discipline | Environment and Geography | |
| dc.degree.level | Master of Science (M.Sc.) | |
| dc.description.abstract | Thwaites Eastern Ice Shelf is the remaining floating extension of Thwaites Glacier, anchored by an offshore pinning point at its northern terminus. Over the past two decades, TEIS has experienced progressive fracturing around a prominent shear zone upstream of its pinning point. Our study analyzes the shear zone fracture evolution from 2002 - 2022 and its control on the flow dynamics of the ice shelf, using remote sensing and in-situ GPS observations. We outlined three areas of interest within TEIS: the pinning-point shear zone, the mid-shelf region, and the region upstream of the pinning point. Then we compiled multi-year shear-zone fracture length and orientation statistics from Landsat and Sentinel-1 imagery and assessed their changes against evolving flow dynamics and shear strain rates. We found that the emergence of the shear zone fractures is dynamically linked with the shelf’s interaction with its neighbouring Thwaites Western Ice Tongue (TWIT) in different phases. These phases include the TWIT-driven acceleration phase (2002-2006), TEIS/TWIT shear-margin disintegration phase (2007-2012), TWIT disintegration phase (2012-2017) and TEIS mid-shelf acceleration phase (2017-2022). Post-2010, we observed the emergence of new rifts from the western part of the shear zone, which localized strain and expanded eastwards in the subsequent years. By 2016-17, the shearing-induced fractures rapidly grew, penetrating the entire shelf width. Subsequently, the mid-shelf ice accelerated eastward, while the ice upstream of the pinning point exhibited deceleration. In the austral winter of 2020, an upstream shift of the line of shearing caused an increase in the mid-shelf ice acceleration, as revealed by in-situ GPS observation. Our findings underscore two insights. First, the ongoing disintegration driven by shearing against the pinning point occurred in a two-stage process: growth of large shearing fractures, externally controlled by the flow of the neighboring TWIT earlier in the record, followed by an internally controlled dense fracturing process resulting from high tensile and shearing stresses. Finally, we show that the shear-zone fracturing process is propelled by a positive feedback mechanism between shearing-induced fracturing and the acceleration of upstream ice, which further amplifies fracturing and exacerbates the shelf's disintegration. | |
| dc.description.note | October 2024 | |
| dc.description.sponsorship | Canada Excellence Research Chair in Arctic Ice, Freshwater Marine Coupling and Climate Change https://doi.org/10.13039/501100000038 | |
| dc.identifier.uri | http://hdl.handle.net/1993/38449 | |
| dc.language.iso | eng | |
| dc.rights | open access | en_US |
| dc.subject | Ice shelves | |
| dc.subject | Antarctica | |
| dc.subject | Thwaites Glacier | |
| dc.subject | Ice-shelf Fractures | |
| dc.subject | Ice-flow Dynamics | |
| dc.subject | Remote Sensing | |
| dc.title | Evolution of shear-zone fractures presages the disintegration of Thwaites Eastern Ice Shelf | |
| dc.type | master thesis | en_US |
| local.subject.manitoba | no | |
| oaire.awardTitle | University of Manitoba Graduate Fellowship (UMGF) | |
| project.funder.identifier | https://doi.org/10.13039/100010318 | |
| project.funder.name | University of Manitoba |