Recovery of isostatic topography over North America from topographic and CHAMP gravity correlations

Laramie V. Potts, C. K. Shum, Ralph Von Frese, Shin Chan Han, Rainer Mautz

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

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.

Original languageEnglish (US)
Title of host publicationEarth Observation with CHAMP
Subtitle of host publicationResults from Three Years in Orbit
PublisherSpringer Berlin Heidelberg
Pages193-198
Number of pages6
ISBN (Print)9783540228042
DOIs
StatePublished - 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

Keywords

  • Hudson Bay
  • correlations
  • crustal thickness
  • gravity
  • topography

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