The presence of triplications (caustics) can be a serious problem in seismic data processing and analysis. The travel-time curve becomes multi-valued and the geometrical spreading correction factor tends to zero due to energy focusing. To select the regions of possible triplications (caustics) of travel-times, which can arise during the propagation of reflected seismic waves, we use the Keller-Maslov-Arnol'd-Hormander (KMAH) index. The identification of such regions improves the selection of signals associated with target reflecting horizons and their use in solving various inverse dynamic problems, including amplitude-versus-offset (AVO) and full-waveform inversions. The importance of the KMAH index increases in 4D surveys when the structure of the model is already known, and it is necessary to conduct a detailed analysis of the shapes of seismic signals with increasing accuracy when solving inverse seismic problems. In addition, this index can be valuable when solving various marine seismic problems associated with single and converted waves, in particular with PSP-waves. The present work is dedicated to the separation of signals associated with this type of wave using surface marine seismic data.
