  Multilayer systems are coupled networks characterized by different contexts
(layers) of interaction and have gained much attention recently due to their
suitability to describe a broad spectrum of empirical complex systems. They are
very fragile to percolation and first-neighbor failure propagation, but little
is known about how they respond to non-local disruptions, as it occurs in
failures induced by flow redistribution, for example. Acknowledging that many
socio-technical and biological systems sustain a flow of some physical
quantity, such as energy or information, across the their components, it
becomes crucial to understand when the flow redistribution can cause global
cascades of failures in order to design robust systems,to increase their
resilience or to learn how to efficiently dismantle them. In this paper we
study the impact that different multiplex topological features have on the
robustness of the system when subjected to non-local cascade propagation. We
first numerically demonstrate that this dynamics has a critical value at which
a small initial perturbation effectively dismantles the entire network, and
that the transition appears abruptly. Then we identify that the excess of flow
caused by a failure is, in general, more homogeneously distributed the networks
in which the average distance between nodes is small.Using this information we
find that aggregated versions of multiplex networks tend to overestimate
robustness, even though to make the system more robust can be achieved by
increasing the number of layers. Our predictions are confirmed by simulated
cascading failures in areal multilayer system.
