The Asymmetric Seismic Moment Tensor in Micropolar Media

Coseismic block rotations are observed in the vicinity of seismogenic faults and have an effect on the moment tensor. This can be accounted for using the linear micropolar theory, which allows the existence of an independent rotation or spin theta different from the continuum rotation 1/2 curl u. In this study, we show that the use of micropolar theory yields asymmetric seismic moment tensors that allow a momentum exchange between the rotational microstructure in the source region and the rest of the Earth and thus explicitly accounts for microstructural rupture processes, which naturally engages a macroscopic displacement response. This work provides a theoretical framework for the development of future dynamic source inversions using micropolar theory.