  Two-dimensional second-order topological superconductors (SOTSCs) have gapped
bulk and edge states, with zero-energy Majorana bound states localized at
corners. Motivated by recent advances in Majorana nanowire experiments, we
propose to realize a tunable SOTSC as a two-dimensional nanowire array. We show
that the coupling between the Majorana modes of adjacent wires can be
controlled by phase-biasing the device, allowing to access a variety of
topological phases. We characterize the system using scattering theory, which
provides access to its transport properties and its topological invariants. The
setup is robust against disorder, both in the nanowires themselves and in the
Josephson junctions formed between adjacent wires. Further, we identify a
parameter regime in which an initially trivial system is rendered topological
upon adding disorder, providing an example of a second-order topological
Anderson phase.
