Seasonal fluctuations in the mass of the Amazon River system and Earth's elastic response

A GPS station in Manaus, near the center of the Amazon basin, manifests an annual cycle of vertical displacement with a peak‐to‐peak amplitude of 50–75 mm. This is by far the largest crustal oscillation observed to date, and nearly 2–3 times larger than the amplitude predicted for this region. Verti...

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Bibliographic Details
Published in:Geophysical research letters 2005-08, Vol.32 (16), p.L16308.1-n/a
Main Authors: Bevis, Michael, Alsdorf, Douglas, Kendrick, Eric, Fortes, Luiz Paulo, Forsberg, Bruce, Smalley Jr, Robert, Becker, Janet
Format: Article
Language:English
Subjects:
Earth sciences
Earth, ocean, space
Exact sciences and technology
Freshwater
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Summary:A GPS station in Manaus, near the center of the Amazon basin, manifests an annual cycle of vertical displacement with a peak‐to‐peak amplitude of 50–75 mm. This is by far the largest crustal oscillation observed to date, and nearly 2–3 times larger than the amplitude predicted for this region. Vertical ground displacement is strongly anti‐correlated with the local stage height of the Amazon river, with no detectable time lag between the two time series. This suggests that we are observing, for the first time, a purely elastic response to changes in the weight of a flowing river system. We use a simple hydrological model to relate stage height to the regional pattern of flooding, and argue that the elastic oscillations observed in Manaus are dominated by changes in water loading developed within ∼200 km of the GPS station.
ISSN:0094-8276
1944-8007
DOI:10.1029/2005GL023491