Open AccessReservoir‐induced deformation and continental rheology in vicinity of Lake Mead, Nevada
Author(s) -
Kaufmann Georg,
Amelung Falk
Publication year - 2000
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jb900079
Subject(s) - geology , canyon , crust , subsidence , viscoelasticity , deformation (meteorology) , viscosity , geomorphology , upper crust , basement , rheology , petrology , geotechnical engineering , geophysics , oceanography , physics , civil engineering , materials science , structural basin , quantum mechanics , engineering , composite material , thermodynamics
Lake Mead is a large reservoir in Nevada, formed by the construction of the 221‐m‐high Hoover Dam in the Black Canyon of the Colorado River. The lake encompasses an area of 635 km 2 , and the total volume of the reservoir is 35.5 km 3 . Filling started in February 1935. On the basis of a first‐order leveling in 1935, several levelings were carried out to measure the deformation induced by the load of the reservoir. Subsidence in the central parts of the lake relative to the first leveling was around 120 mm (1941), 218 mm (1950), and 200 mm (1963). The subsidence pattern clearly shows relaxation of the underlying basement due to the water load of the lake, which ceased after 1950. Modeling of the relaxation process by means of layered, viscoelastic, compressible flat Earth models with a detailed representation of the spatial and temporal distribution of the water load shows that the thickness of the elastic crust underneath Lake Mead is 30±3 km. The data are also consistent with a 10‐km‐thick elastic upper crust and a 20‐km‐thick viscoelastic lower crust, with 10 20 Pa s as a lower bound for its viscosity. The subcrust has an average viscosity of 10 18±0.2 Pa s, a surprisingly low value. The leveling data constrain the viscosity profile down to ∼200 km depth.