Crustal deformation by earthquakes and explosions

Static displacements were calculated for an earth model which consists of a single layer of thickness H overlying a homogeneous half space. Localized sources simulating earthquake and explosion foci are placed at depths h=H2andh=32H. The ensuing surface deformation is evaluated as a function of the epicentral distance for a typical continental crust model. A new technique is used for the quadrature of the displacement integrals. By this method one is able to calculate 1000 layer-integrals of the type F m n ( x , t ) = ∫ 0 ∞ y n e − x y J m ( t y ) d y 1 + ( A + B y 2 ) e − 2 y + D e − 4 y , with an accuracy of 0.1 per cent, in less than 2 minutes. It is found that for epicentral distances r > 20H the displacements decay like (r/H)−α where 2 < α < 5. For compressional and strike-slip displacements at all depths and for dip-slip source above the layer, 2 < α < 3. For a dip-slip source located below the layer, 3 < α < 5. Maximal displacements for wr, ur, ux, uy and uz occur at approximately r ≃ 0.8h and decay with source's-depth like h−3/2.