2005 | OriginalPaper | Buchkapitel
Recovery of Isostatic Topography over North America from Topographic and CHAMP Gravity Correlations
verfasst von : Laramie V. Potts, C. K. Shum, Ralph von Frese, Shin-Chan Han, Rainer Mautz
Erschienen in: Earth Observation with CHAMP
Verlag: Springer Berlin Heidelberg
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We investigate North American crustal structure and mass loads from spectral correlation analysis of topographic, CHAMP and terrestrial gravity data. We use free-air and terrain gravity correlations to isolate tectonically driven vertical motions and mass imbalances of the crust and lithosphere. Specifically, we apply correlation filters to decompose the free-air gravity anomalies into terrain-correlated and terrain-decorrelated components to yield compensated terrain gravity effects that we evaluate for crustal thickness variations. Our results compare quite favourably with the seismically inferred global crustal thickness model Crust5.1 and a 3.4 km rms difference with LITH5.0 over North America. Terrain-correlated anomalies reveal mass excesses and deficits that are interpreted as uncompensated elements of the crust. For Hudson Bay, the average terrain-correlated free-air anomaly suggests that the crustal topography is depressed by about 400 m. Because glacial isostatic adjustment considerations can only marginally account for the depression, we speculate that it may reflect other effects such as a preglacial impact.