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Glacier Ice Mass Fluctuations and Fault Instability in Tectonically Active Southern AlaskaAcross southern Alaska the northwest directed subduction of the Pacific plate is accompanied by accretion of the Yakutat terrane to continental Alaska. This has led to high tectonic strain rates and dramatic topographic relief of more than 5000 meters within 15 km of the Gulf of Alaska coast. The glaciers of this area are extensive and include large glaciers undergoing wastage (glacier retreat and thinning) and surges. The large glacier ice mass changes perturb the tectonic rate of deformation at a variety of temporal and spatial scales. We estimated surface displacements and stresses associated with ice mass fluctuations and tectonic loading by examining GPS geodetic observations and numerical model predictions. Although the glacial fluctuations perturb the tectonic stress field, especially at shallow depths, the largest contribution to ongoing crustal deformation is horizontal tectonic strain due to plate convergence. Tectonic forces are thus the primary force responsible for major earthquakes. However, for geodetic sites located < 10-20 km from major ice mass fluctuations, the changes of the solid Earth due to ice loading and unloading are an important aspect of interpreting geodetic results. The ice changes associated with Bering Glacier s most recent surge cycle are large enough to cause discernible surface displacements. Additionally, ice mass fluctuations associated with the surge cycle can modify the short-term seismicity rates in a local region. For the thrust faulting environment of the study region a large decrease in ice load may cause an increase in seismic rate in a region close to failure whereas ice loading may inhibit thrust faulting.
Document ID
20040030573
Acquisition Source
Headquarters
Document Type
Preprint (Draft being sent to journal)
Authors
SauberRosenberg, Jeanne M. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Molnia, Bruce F. (Geological Survey Reston, VA, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2003
Subject Category
Geosciences (General)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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