Isostasy - Isostatic Models

Isostatic Models

Three principal models of isostasy are used:

• The Airy-Heiskanen Model

- where different topographic heights are accommodated by changes in crustal thickness, in which the crust has a constant density

• The Pratt-Hayford Model

- where different topographic heights are accommodated by lateral changes in rock density.

• The Vening Meinesz, or flexural isostasy model

- where the lithosphere acts as an elastic plate and its inherent rigidity distributes local topographic loads over a broad region by bending.

Airy and Pratt isostasy are statements of buoyancy, while flexural isostasy is a statement of buoyancy while deflecting a sheet of finite elastic strength.