Abstract Microseismic results are presented for hydraulic fracture stimulations monitored in the Cotton Valley, East Texas. In particular, we examine whether additional information on the microseismic source such as the apparent stress release values can be used to effectively identify differences in the generation process of individual or clusters of microseismic events and the development of the overall hydraulic fracture in both space and time. Trends in apparent stress have been used to establish different modes of failure, with increased apparent stress values at the leading edge of the hydraulic fracture and lower apparent stress values behind the leading edge. We suggest that the failures are along a pre-existing network of fractures and include significant non-shear components of failure for events occurring behind the hydraulic fracture front. At the extremities of the hydraulic fracture as the stimulation proceeds we suggest that the redistribution of stresses as a result of the injection increase the average shear driving stress resulting in shear dominated failures. Overall, the hydraulic fracture can be characterized by regions of shear and nonshear type failures, further suggesting that the relative permeability of the fracture network can possibly be identified.