We present results of fully compressible Navier-Stokes simulations of pulsating flame instabilities in two dimensions using single-step, first-order Arrhenius kinetics. Model parameters correspond to Zel'dovich and Lewis numbers of Ze = 9.5 and Le = 10, respectively, and flame Mach numbers M-L between 4.62 x 10(-3) and 2.31 x 10(-2). The results show that the pulsating instability creates two types of transverse waves: deflagrations and detonations. Both types of waves can coexist for the same reactive system, but transverse detonations become more likely as M-L increases. The transverse detonations observed for our model system are of the intermediate type with most of the chemical energy release accompanying the pressure rise. They propagate inside the large preheat zone of the pulsating flame and do not spread into cold material. The results expand our knowledge of possible new phenomena associated with pulsating instability. Published by Elsevier Inc. on behalf of The Combustion Institute.