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Crustal displacements due to continental water loading
Author(s) -
van Dam T.,
Wahr J.,
Milly P. C. D.,
Shmakin A. B.,
Blewitt G.,
Lavallée D.,
Larson K. M.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl012120
Subject(s) - geology , amplitude , geodesy , tectonics , tilt (camera) , series (stratigraphy) , sea level , global positioning system , ocean tide , climatology , seismology , geometry , oceanography , physics , mathematics , paleontology , telecommunications , quantum mechanics , computer science
The effects of long‐wavelength (>100 km), seasonal variability in continental water storage on vertical crustal motions are assessed. The modeled vertical displacements (Δ r M ) have root‐mean‐square (RMS) values for 1994–1998 as large as 8 mm, with ranges up to 30 mm, and are predominantly annual in character. Regional strains are on the order of 20 nanostrain for tilt and 5 nanostrain for horizontal deformation. We compare Δ r M with observed Global Positioning System (GPS) heights (Δ r O ) (which include adjustments to remove estimated effects of atmospheric pressure and annual tidal and non‐tidal ocean loading) for 147 globally distributed sites. When the Δ r O time series are adjusted by Δ r M , their variances are reduced, on average, by an amount equal to the variance of the Δ r M . Of the Δ r O time series exhibiting a strong annual signal, more than half are found to have an annual harmonic that is in phase and of comparable amplitude with the annual harmonic in the Δ r M . The Δ r M time series exhibit long‐period variations that could be mistaken for secular tectonic trends or postglacial rebound when observed over a time span of a few years.