The S reflector and rifting processes: Iberia Abyssal Plain/Galicia Bank

Funded by NSF Marine Geology and Geophysics Program, 1997 (Dale Sawyer PI).

2D and 3D velocity structure of the Iberia margin from the inversion of wide-angle and near-vertical traveltime data

Fig.1. Survey geometry of the Iberia seismic experiment. Circles and triangles show OBS and OBH locations and colored lines are airgun profiles. Only lines with OBS/OBH coverage are labeled; all lines have MCS coverage. Land stations that recorded the airgun shots are also indicated. Only data from lines 1, 4, 5 and 6 have been considered so far.

Fig. 2. Seismic phases used in obtaining the 2D velocity models for lines 1 and 5 using the traveltime inversion method of Zelt and Smith (1992). Ps, Pg, and Pn are wide-angle refracted arrivals though the sediments, crust and upper mantle. PmP is the wide-angle reflected arrival from the Moho. Reflections picked from the unmigrated MCS data (Fig. 7) were jointly inverted with the wide-angle data, including reflections from the sediments, the S reflector/mantle, and features in the crust and mantle that do not coincide with layer boundaries or velocity discontinuities in the model but were treated as "floating reflectors".