  Failure in disordered solids is accompanied by intermittent fluctuations
extending over a broad range of scales. The implied scaling has been previously
associated with either spinodal or critical points. We use an analytically
transparent mean-field model to show that both analogies are relevant near the
brittle-to-ductile transition. Our study indicates that in addition to the
strength of quenched disorder, an appropriately chosen global measure of
rigidity (connectivity) can be also used to tune the system to criticality. By
interpreting rigidity as a timelike variable we reveal an intriguing parallel
between earthquake-type critical failure and Burgers turbulence.
