CGRG Bibliography of Canadian Geomorphology
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Author : Fenton, C.H.
Date : 2002.
Title : Postglacial faulting: knowns and unknowns.
Publication : American Geophysical Union Meeting, Spring 2002. Washington Convention Center, Washington, DC. 28 - 31 May 2002.
Issue :
Page(s) :
Abstract
Irregularities in glacio-isostatic uplift patterns, shown by gradient changes and discontinuities in uplifted shoreline profiles, highlight the non-uniform nature of glacial rebound. Discrete discontinuities in shoreline profiles indicate that uplift heterogeneities are accommodated by fault movement in the brittle crust. Such glacio-isostatic faults are triggered by changes in the glacial load: either as a result of deglaciation (crustal unloading) or glacial advance (crustal loading). Also known as "postglacial faults", these faults have been recorded in many regions of former ice cover, including northwest Europe (Norway, Sweden, Finland, Russia, Eire, and Scotland) and North America (eastern Canada, New England, and possibly California and Montana). To date, all examples of postglacial faulting have been recorded in regions of low to moderate seismicity, namely passive margin, failed rift, or intraplate/craton environments. With the notable exception of the 1989 M 6.1 Ungava surface rupture in northern Quebec, postglacial faults are unique in that they occur in regions where there is no evidence of surface rupture during historical time. In addition, these regions have no historical record of seismicity that approaches the magnitude thresholds for generating surface faulting. All examples of postglacial faulting have involved reactivation of existing faults and fractures. This presentation will review the characteristics of postglacial faults and examine some of the examples that have erroneously been attributed to glacio-isostatic triggering. The characteristics of paleoseismic phenomena associated with glacio-isostatic faulting, including liquefaction and landsliding, will be reviewed. Finally the timing of faulting relative to ice sheet fluctuations and if the effects of glacial loading are still sufficient to trigger future fault activity will also be discussed.
Bibliography of Canadian Geomorphology