2D seismic, echosounder and multibeam data of the Witch Ground Basin (central North Sea) during Maria S. Merian cruise MSM63

High-resolution 2D seismic reflection data during research cruise MSM63 in April/May 2017 onboard RV Maria S. Merian. The seismic profiles were acquired with a two-105/105-in3-GI-Gun-array shot at 210 bar every 5 seconds and a 150 m-long streamer with 96 channels and 1.5625 m channel spacing. The resulting shot point distance is approximately 8.75-12.5 m at 3.5-5 kn ship speed. The frequency range of the two-GI-Gun-array is 15-500 Hz. The processing included geometry and delay corrections, static corrections, binning to 1.5625 m and bandpass filtering with corner frequencies of 25, 45, 420, and 500 Hz. Furthermore, a normal-move-out-correction (with a constant velocity of 1488 m/s calculated from CTD measurements) was applied and the data were stacked and then migrated using a 2D Stolt algorithm (1500 m/s constant velocity model).

Sub-bottom profiler data acquired during cruise MSM63 using Parasound P70 with 4 kHz as the secondary low frequency to obtain seismic images of the upper 100 m below the seafloor with very high vertical resolution (< 15 cm). We applied a frequency filter (low cut 2 kHz, high cut 6 kHz, 2 iterations) and calculated the envelope within the seismic interpretation software IHS Kingdom.

Bathymetric data were acquired with the EM712 system mounted to the hull of RV Maria S. Merian. The survey was designed to provide high-resolution bathymetry with 5 x 5 m resolution. We processed the data using MB Systems software (Caress & Chayes, 2017) and included statistical evaluation of soundings that increased the signal-to-noise ratio. The sound velocity profile for multibeam processing was measured at the beginning and at the end of the cruise.