Active Tectonics, Glacier Load History and Post-Little-Ice-Age Isostatic Rebound in Southeastern Alaska

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This study is part is an interdisciplinary program to determine the spatial and temporal characteristics of ongoing crustal deformation in the northern part of southeastern Alaska (latitude 57 to 62). The target of this investigation is a region that is currently experiencing the highest rates of uplift in the world (25 to 40 mm/yr) and where relative plate motion is 50 mm/yr. Preliminary results show an interesting and very exciting pattern of uplift and tectonic strain accumulation in southeastern Alaska.A network of 80+ campaign GPS sites established during a prior study are being re-occupied to fill gaps in delineation of the spatial and temporal characteristics of current uplift and horizontal crustal deformation, and to improve the precision at most of the sites. Two sites are being examined to determine Little Ice Age and post-Little Ice Age uplift history from dendrochronology and geomorphology. This additional data will fill gaps in both far-field locations where uplift is lowest and in regions where uplift has been greatest, providing better temporal and spatial control on decadal and centennial time scales. The results of these field investigations are being used to develop two- and three-dimensional isostatic rebound models, to analyze plate tectonic deformation, and to evaluate the relationship between glaciations and tectonics in the northern part of southeast Alaska.