Abstract: In general, there are two failure modes in heterogeneousbrittle materials, the gradual failure and the catastrophic failure. Thepaper analyses the differences between the gradual failure and thecatastrophic failure based on statistical mesoscopic damage mechanics. Theresults show that the ratio of the released elastic energy to the damagedissipative energy can be served as a sensitive precursor of catastrophe.Furthermore the value of the non-dimensional ratio has a similar tendency tobe 1 with different responses in the two failure modes, that is, theresponse function R always decreases in the gradual mode, while increasesand tends to be infinite at the catastrophic point of the failure.