2-DIMENSIONAL CRUSTAL VELOCITY STRUCTURE ALONG HIRAPUR-MANDLA PROFILEFROM SEISMIC-REFRACTION AND WIDE-ANGLE REFLECTION DATA

The seismic velocity structure of the upper and lower crusts along Hir apur-Mandla profile was obtained by 2-D forward modeling of the refrac tion and wide-angle reflection data. Digitized record sections of the analog data were utilized for delineation of the crustal velocity mode l across the Vindhyan basin and the Narmada-Son lineament by travel-ti me modeling and qualitatively matching the amplitudes of synthetic sei smograms with seismic record sections. An interface at a depth of 8 km has been traced from wide-angle reflection data of shot points 160 an d 235 between Jabalpur and Mandla. The wide-angle reflection phase fro m crust-mantle boundary is very prominent in all the seismic record se ctions of shot points 0, 40, 80, 120 and 235. The Moho horizon along t he entire study area was continuously traced, depicting an upwarp betw een Katangi and Jabalpur below the Narmada-Son lineament. The three fa ults inferred near Narsinghgarh, Katangi and Jabalpur divide the crust into four blocks. The number of faults and displacement patterns alon g them, depicted along the profile, indicates that block tectonics app ear to be active in this region throughout the geological history.