09:45 〜 10:00
[SIT26-04] Numerical simulations of the formation of a dynamic decollement
キーワード：accretionary prism, decollement
Decollements are often weak sedimentary layer that are deformed preferentially to form the base of an accretionary prism. However, in the Nankai Trough there is no clear evidence of a particular precursory layer. In this contribution, we discuss the mechanical conditions which can lead to the formation of a near horizontal thrust that acts as the basal shear zone of an accretionary prism. We performed numerical simulations of the deformation of a visco-elasto-plastic material with sandbox-type boundary conditions. We show that the imposed kinematic boundary condition lead to a stress state that allow for both the development of Andersonian fault that develop from the surface and non-andersonian, near horizontal fault that propagate from the indenter. Results from this simple numerical experiment are discussed in the light of available stress data from the Nankai accretionary prism.