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Possible mechanisms for glacial earthquakes

Tsai, Victor C. and Rice, James R. and Fahnestock, Mark (2008) Possible mechanisms for glacial earthquakes. Journal of Geophysical Research F, 113 (F3). Art. No. F03014. ISSN 0148-0227. doi:10.1029/2007JF000944.

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The large glacial earthquakes reported on by Ekström et al. (2003, 2006) and Tsai and Ekström (2007) have previously been evaluated in terms of their seismic characteristics. In this paper we attempt to take constraints such as known glacial ice properties, outlet glacier size, calving style, and meltwater variability to construct a self-consistent physical model of the glacial earthquake process. Since many glaciological parameters are poorly constrained, we parameterize a number of important processes and estimate a wide range of possible values for some properties. The range of model outputs is thus fairly large, but it is still difficult to match observational constraints under most conditions. We find that only a small class of models is able to satisfy the major observational constraints. These models are characterized by (1) lost basal resistance coupled to viscoelastic deformation with extensive internal crevassing or with low effective elastic modulus and possibly low effective viscosity or (2) by nonequilibrium calving, such as having large icebergs capsize into the glacier front. Although observational constraints cannot definitively rule out any of the proposed classes of mechanisms, the calving model has much stronger support. Fortunately, the various models make different predictions regarding observables that can potentially be measured in the near future.

Item Type:Article
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URLURL TypeDescription Information
Tsai, Victor C.0000-0003-1809-6672
Additional Information:© 2008 American Geophysical Union. Received 7 November 2007; revised 9 June 2008; accepted 1 July 2008; published 5 August 2008. We thank I. Joughin, R. B. Alley, I. M. Howat, M. Nettles, and G. Ekström for helpful discussion, and we thank S. O’Neel, M. Truffer, and S. Tulaczyk for constructive reviews. This work was supported by a National Science Foundation Graduate Research Fellowship to V.C.T. and, in its later stages, by NSF-OPP grant ANT-0739444.
Group:Seismological Laboratory
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Subject Keywords:glacial earthquake; icequake; calving
Issue or Number:F3
Record Number:CaltechAUTHORS:20140702-101254626
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Official Citation:Tsai, V. C., J. R. Rice, and M. Fahnestock (2008), Possible mechanisms for glacial earthquakes, J. Geophys. Res., 113, F03014, doi:10.1029/2007JF000944.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46631
Deposited On:02 Jul 2014 21:57
Last Modified:10 Nov 2021 17:28

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