Coseismic rotations of principal stress axes can provide insights into
the strength of the crust, but it is unclear how common this phenomenon
is. We use a nearest-neighbor clustering algorithm to identify
earthquake sequences in the global ISC-GEM catalog and the regional
Southern California catalog. Using an inner-product-based pairwise
measure of moment tensor similarity, we demonstrate that, in both
catalogs, aftershocks are less similar to their respective mainshocks
than foreshocks are. We interpret this effect, which we call moment
tensor scattering, as evidence for widespread coseismic stress
rotations. Moment tensor scattering is observable for a broad range of
mainshock magnitudes in both catalogs. We further demonstrate that
mainshock-aftershock similarity recovers logarithmically to
pre-mainshock levels on decadal timescales. We conclude that moment
tensor scattering is a generally observable feature of seismic sequences
which may be useful in future work to discriminate between models of
crustal strength.