STOCHASTIC MODELING OF SEISMIC SURFACE ROTATIONS

In this paper, a stochastic analysis of surface rotations during earthquakes is presented. The surface motion is modeled by a spacetime random field. A method to obtain rotation based on direct differentiation of the random field is proposed with a reference to a second method based on wave decomposition. The first method leads to a spectral density of surface rotations in terms of point translation spectral density, coherence function and apparent waves velocity, while the second method formulates the rotational spectrum in terms of point translation spectral density and wave parameters. The advantages and disadvantages of both methods are discussed in detail.