Abstract:
This award supports a project to strengthen collaborations between the various research groups working on iceberg calving. Relatively little is known about the calving process, especially the physics that governs the initiation and propagation of fractures within the ice. This knowledge gap exists in part because of the diverse range in spatial and temporal scales associated with calving (ranging ... from less than one meter to over a hundred kilometers in length scale). It is becoming increasingly clear that to predict the future behavior of the Antarctic Ice Sheet and its contribution to sea level rise, it is necessary to improve our understanding of iceberg calving processes. Further challenges stem from difficulties in monitoring and quantifying short-time and spatial-scale processes associated with ice fracture, including increased fracturing events in ice shelves or outlet glaciers that may be a precursor to disintegration, retreat or increased calving rates. Coupled, these fundamental problems currently prohibit the inclusion of iceberg calving into numerical ice sheet models and hinder our ability to accurately forecast changes in sea level in response to climate change. Seismic data from four markedly different environmental regimes forms the basis of the proposed research, and researchers most familiar with the datasets will perform all analyses. Extracting the similarities and differences across the full breadth of calving processes embodies the core of the proposed work, combining and improving methods previously developed by each group. Techniques derived from solid Earth seismology, including waveform cross-correlation and clustering will be applied to each data set allowing quantitative process comparisons on a significantly higher level than previously possible. This project will derive catalogues of glaciologically produced seismic events; the events will then be located and categorized based on their location, waveform and waveform spectra both within individual environments and between regions.
Purpose:
The intellectual merit of this work is that it will lead to a better understanding of iceberg calving and the teleconnections between seismic events and other geophysical processes around the globe. The broader impacts of this work are that it relates directly to socio-environmental impacts of global change and sea level rise.
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
City:
Boulder
Province or State:
CO
Postal Code:
80309-0449
Country:
USA
Publications/References
Alley, RB; Horgan, HJ; Joughin, I; Cuffey, KM; Dupont, TK; Parizek, BR; Anandakrishnan, S; Bassis, J. "A Simple Law for Ice-Shelf Calving," SCIENCE, v.322, 2008, p. 1344-1344. View record at Web of Science
Douglas R. MacAyeal, Emile A. Okal, Richard C. Aster, Jeremy N. Bassis. ") Seismic observations of glaciogenic ocean waves (micro-tsunamis) on icebergs and ice shelves," Journal of Glaciology, ... v.55, 2009.
MacAyeal, DR; Okal, EA; Aster, RC; Bassis, JN. "Seismic and hydroacoustic tremor generated by colliding icebergs," JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE, v.113, 2008. View record at Web of Science
Pfeffer, WT; Harper, JT; O'Neel, S. "Kinematic constraints on glacier contributions to 21st-century sea-level rise," SCIENCE, v.321, 2008, p. 1340-1343. View record at Web of Science
Walter, F; O'Neel, S; McNamara, D; Pfeffer, WT; Bassis, JN; Fricker, HA. "Iceberg calving during transition from grounded to floating ice: Columbia Glacier, Alaska," GEOPHYSICAL RESEARCH LETTERS, v.37, 2010. View record at Web of Science
Walter, F; Amundsun, JM; O'Neel, S; Truffer, MT; Fahnestock, M; Fricker, HA. "Analysis of low-frequency seismic signals generated during a multiple-iceberg calving event at Jakobshavn Isbræ, Greenland," JOURNAL OF GEOPHYSICAL RESEARCH, v. 117, F01036, 2012
