An extensive study for Langmuir monolayer collapse is carried out to explore the generality of classification of their crack patterns (E. Hatta et al. Eur. Phys. J. 1999, B 11, 609) and to analyze crack kinetics in the anisotropic cracks. Upon compression of fatty acid monolayers beyond the collapse pressure three classes of fracture patterns, a surface roughening, random crack network, or anisotropic fracture, can be observed depending on chain length of the fatty acid, pH value, and ion concentration of the subphase. A statistical characterization of the anisotropic crack growth of Langmuir monolayer fracture is presented. Anisotropic cracks grow on a Co2+ water subphase as quasi-periodic modulations, branching off previously formed cracks, interrupted by the coalescence of modulation cracks. Slight changes in pH and concentration of Co2+ ions in the subphase cause drastic changes of the modulation crack coalescence rate. We suggest, that differences in the viscoelastic nature of the monolayer are the main causes for the three types of crack growth scenaria.