A defining characteristic of fractured rocks is their very high level
of seismic attenuation, which so far has been assumed to be mainly
due to wave-induced fluid flow (WIFF) between the fractures and the
pore space of the embedding matrix. Using oscillatory compressibility
simulations based on the quasi-static poroelastic equations, we show
that another important, and as of yet undocumented, manifestation
of WIFF is at play in the presence of fracture connectivity. This
additional energy loss is predominantly due to fluid flow within
the connected fractures and is sensitive to their lengths, permeabilities,
and intersection angles. Correspondingly, it contains key information
on the governing hydraulic properties of fractured rock masses and
hence should be accounted for whenever realistic seismic models of
such media are needed.