Seismic radiation from regions sustaining material damage

We discuss analytical results for seismic radiation during rapid episodes of inelastic brittle deformation that include, in addition to the standard moment term, a damage-related term stemming from changes of elastic moduli in the source region. The radiation from the damage-related term is associated with products of the changes of elastic moduli and the total elastic strain components in the source region. Order of magnitude estimates suggest that the damage-related contribution to the motion in the surrounding elastic solid, which is neglected in standard calculations, can have appreciable amplitude that may in some cases be comparable to or larger than the moment contribution. A decomposition analysis shows that the damage-related source term has an isotropic component that can be larger than its double-couple component.