Mapping the Moho beneath the southern Urals with wide-angle reflections

A stack of the wide-angle reflection/refraction component of the URSEIS-95 experiment provides the first well-resolved imaged of the Moho beneath the southern Urals. The processing consisted of low pass filter (0 - 6 Hz), CMP sorting, and a NMO correction without stretch. The PmP phase, a very narrow band and low frequency (up to 6 Hz) wavelet, changes character from west to east along the transect. In the depth converted section, the Moho reaches a maximum depth of 53 +/- 2 km beneath the Magnitogorsk are. Thickness estimates determined from high amplitudes at near critical distances also support a 53 km thick crust. A selective offset stack consisting of traces at 150 - 250 km offset indicate an undulating, irregular Moho, suggesting either strong lateral velocity variations or high topographic relief beneath the Magnitogorsk arc.