  We report arrays of monodisperse water-in-oil microdroplets printed onto a
substrate in a form of a compact linear chain -- a 1D-crystal -- pinned at one
end. The chain spontaneously collapses under capillary forces via a sequence of
avalanche-like rearrangement waves, resembling the rearrangements in a flowing
microfluidic crystal, yet limited by the hydrodynamic friction at the
substrate. While the propagation of the subsequent waves, separated by highly
ordered metastable states, is either accelerating or decelerating depending on
the direction of collapse, the coarse-grained dynamics of multiple waves -- at
moderate packing fractions $\phi$ -- is initially linear in time, before
leveling off. We further demonstrate how the collapse can be prevented via the
use of a roughened substrate. Our study provides insight into the short- and
long-term avalanche dynamics in granular systems with free interfaces and opens
way to precision-printing of microfluidic assays.
