  The structure of real-world multilayer infrastructure systems usually
exhibits anisotropy due to constraints of the embedding space. For example,
geographical features like mountains, rivers and shores influence the
architecture of critical infrastructure networks. Moreover, such spatial
networks are often non-homogeneous but rather have a modular structure with
dense connections within communities and sparse connections between neighboring
communities. When the networks of the different layers are interdependent,
local failures and attacks may propagate throughout the system. Here we study
the robustness of spatial interdependent networks which are both anisotropic
and heterogeneous. We also evaluate the effect of localized attacks having
different geometrical shapes. We find that anisotropic networks are more robust
against localized attacks and that anisotropic attacks, surprisingly, even on
isotropic structures, are more effective than isotropic attacks.
