Horizontal strain rate distribution on an active ice shelf rift from in-situ GPS data

• Main Author: Janssen, V
• Format: Article in Journal/Newspaper
• Language: English
• Published: University of Calgary 2009
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Glaciology; Amery; Amery Ice Shelf; Antarctic; The Antarctic; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves; Iceberg*
• Online Access: http://www.cpgps.org/journal.php; http://ecite.utas.edu.au/59836

Mass loss from the Antarctic ice sheet predominantlyoccurs at the fringing ice shelves via iceberg calving,which is controlled by the initiation and propagation oflarge rifts that precede iceberg detachment and can leadto ice shelf break-up. This paper reports on the analysis ofGlobal Positioning System (GPS) data collected at anactive rift system on the Amery Ice Shelf, EastAntarctica, over two field seasons. Horizontal strain ratesare determined for a network of 11 sites observed overthree weeks during the 2004/05 Antarctic summer period,and the results are combined with, and compared to,strain rates obtained in the 2002/03 season. Maximumprincipal strain rates across the network vary between 6and 32 [x 10-3/yr], while minimum principal strain ratesare generally about 1-17 [x 10-3/yr]. Changes evident inthe strain distribution can mostly be attributed to existingfractures passing through the GPS network and theepisodic movement of the rift tip. It is confirmed that riftpropagation in 2005/06 was slowing down. Opening ratesare inferred from baselines situated normal to the rift.Analysis of the network using a cumulative sum approachis found to be an effective method to detect smallbaseline length changes associated with rift propagation.