Dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations
Iceberg calving accounts for two thirds of the mass discharged from the cryosphere to the ocean. Despite the prominent role that iceberg calving plays in the mass balance of ice sheets and glaciers, it remains one of the most poorly understood glaciological processes. Iceberg calving is preceded by...
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ftcdlib:oai:escholarship.org/ark:/13030/qt8hc8q0k5 2023-05-15T13:22:11+02:00 Dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations Bassis, Jeremy N. 2007-01-01 application/pdf https://escholarship.org/uc/item/8hc8q0k5 unknown eScholarship, University of California qt8hc8q0k5 https://escholarship.org/uc/item/8hc8q0k5 public etd 2007 ftcdlib 2020-06-06T07:55:56Z Iceberg calving accounts for two thirds of the mass discharged from the cryosphere to the ocean. Despite the prominent role that iceberg calving plays in the mass balance of ice sheets and glaciers, it remains one of the most poorly understood glaciological processes. Iceberg calving is preceded by the formation and propagation of fractures that sever the entire ice thickness. These fractures, known as rifts, can propagate for decades before an iceberg detaches. This dissertation presents results from three targeted field campaigns of geodetic and seismic measurements around the tip of a propagating rift on the Amery Ice Shelf, East Antarctica in 2002-03, 2004-05 and 2005-06. These observations are the first in situ measurements of rift propagation on an ice shelf. Chapter 1 provides the motivation and background that inspired a detailed study of ice shelf rifting. Chapter 2 presents results from the first field season where it was shown that rift propagation is episodic. In Chapter 3 the detailed seismic network that was installed over the following two field seasons was exploited to accurately map the spatial and temporal trends in seismicity. In Chapter 4 data from automatic weather stations were used in combination with field measurements to show that neither winds, ocean currents nor tides trigger rift propagation. In Chapter 5 we look at vertical deformation around the rift using data from both our global positioning system receivers and elevation profiles across the rift obtained from a satellite laser altimeter (ICESat). Using these two data sources, we show that the pattern of deformation along the rift walls is consistent with normal faulting. In Chapter 6 we derive an empirical non-dimensional stability parameter that predicts when unstable retreat of tidewater glaciers and ice shelves will occur. The stability parameter is validated using data from several Alaskan tidewater glaciers, two Greenland glaciers and three Antarctic ice shelves. Chapter 7 summarizes the work done and suggests directions for future research Other/Unknown Material Amery Ice Shelf Antarc* Antarctic Antarctica East Antarctica Greenland Ice Shelf Ice Shelves Iceberg* University of California: eScholarship Amery ENVELOPE(-94.063,-94.063,56.565,56.565) Amery Ice Shelf ENVELOPE(71.000,71.000,-69.750,-69.750) Antarctic East Antarctica Greenland Sever ENVELOPE(166.083,166.083,62.917,62.917) |
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University of California: eScholarship |
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description |
Iceberg calving accounts for two thirds of the mass discharged from the cryosphere to the ocean. Despite the prominent role that iceberg calving plays in the mass balance of ice sheets and glaciers, it remains one of the most poorly understood glaciological processes. Iceberg calving is preceded by the formation and propagation of fractures that sever the entire ice thickness. These fractures, known as rifts, can propagate for decades before an iceberg detaches. This dissertation presents results from three targeted field campaigns of geodetic and seismic measurements around the tip of a propagating rift on the Amery Ice Shelf, East Antarctica in 2002-03, 2004-05 and 2005-06. These observations are the first in situ measurements of rift propagation on an ice shelf. Chapter 1 provides the motivation and background that inspired a detailed study of ice shelf rifting. Chapter 2 presents results from the first field season where it was shown that rift propagation is episodic. In Chapter 3 the detailed seismic network that was installed over the following two field seasons was exploited to accurately map the spatial and temporal trends in seismicity. In Chapter 4 data from automatic weather stations were used in combination with field measurements to show that neither winds, ocean currents nor tides trigger rift propagation. In Chapter 5 we look at vertical deformation around the rift using data from both our global positioning system receivers and elevation profiles across the rift obtained from a satellite laser altimeter (ICESat). Using these two data sources, we show that the pattern of deformation along the rift walls is consistent with normal faulting. In Chapter 6 we derive an empirical non-dimensional stability parameter that predicts when unstable retreat of tidewater glaciers and ice shelves will occur. The stability parameter is validated using data from several Alaskan tidewater glaciers, two Greenland glaciers and three Antarctic ice shelves. Chapter 7 summarizes the work done and suggests directions for future research |
format |
Other/Unknown Material |
author |
Bassis, Jeremy N. |
spellingShingle |
Bassis, Jeremy N. Dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations |
author_facet |
Bassis, Jeremy N. |
author_sort |
Bassis, Jeremy N. |
title |
Dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations |
title_short |
Dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations |
title_full |
Dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations |
title_fullStr |
Dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations |
title_full_unstemmed |
Dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations |
title_sort |
dynamics of ice shelf rift propagation and iceberg calving inferred from geodetic and seismic observations |
publisher |
eScholarship, University of California |
publishDate |
2007 |
url |
https://escholarship.org/uc/item/8hc8q0k5 |
long_lat |
ENVELOPE(-94.063,-94.063,56.565,56.565) ENVELOPE(71.000,71.000,-69.750,-69.750) ENVELOPE(166.083,166.083,62.917,62.917) |
geographic |
Amery Amery Ice Shelf Antarctic East Antarctica Greenland Sever |
geographic_facet |
Amery Amery Ice Shelf Antarctic East Antarctica Greenland Sever |
genre |
Amery Ice Shelf Antarc* Antarctic Antarctica East Antarctica Greenland Ice Shelf Ice Shelves Iceberg* |
genre_facet |
Amery Ice Shelf Antarc* Antarctic Antarctica East Antarctica Greenland Ice Shelf Ice Shelves Iceberg* |
op_relation |
qt8hc8q0k5 https://escholarship.org/uc/item/8hc8q0k5 |
op_rights |
public |
_version_ |
1766363648595329024 |