Lithospheric plates are exerted by a fluid pressure,since they immediately overlie the asthenosphere. We define this fluid pressure as Asthenospheric Static Push (ASP). For a oceanic plate,there is no difference of ASP and the traditional ridge push force. Assuming a decoupling of horizontal components and vertical component of the intraplate stresses,we have the two horizontal components of the intraplate stresses due to the ASP and other forces using the 2-D spherical finite element modeling,and the vertical component by isostasy. A differential stress field is obtained by subtracting the vertical component of stresses from the horizontal components.
By introducing the concept of ASP,it is convenient to use the observed stress regimes as constraints to study the problems of plate dynamics and to explain the observed complex stress patterns in the transition regions between the sea and the continent and those in the anomalous gravity regions.