3,393 km on 24 lines of seismic reflection, gravimetric and magnetometric survey of Weddell Sea, divided into the following areas: Area 1 - Hero Fracture Zone: about 2,607 km on 16 lines; Area 2 - Bransfield Strait : about 561 km on 6 lines; Area 3 - Scotia Arc : about 225 km on 2 lines.

Gravity; Seismic reflection

Multi-channel seismic reflection systems; seismic refraction systems; gravimeters; satellite positioning systems

During February and March 1992, the OGS carried out an Antarctic Campaign in the seas surrounding the Antarctic Peninsula. The research has been carried out in the framework of the National Research Program in Antarctica coordinated by ENEA under the auspices of the Italian Ministry for Scientific Research. The survey has been dedicated to three different areas where data have been collected with different sampling parameters. The first area of investigation was conducted in the Hero Fracture Zone. In this area, 16 lines have been acquired with 'standard sampling parameters' for a total of 2607 km. The second area investigated during the survey was the Bransfield Strait. Due to the moderate ice coverage and the particular conformation of the area, it was necessary to use a shorter streamer and a reduced airgun array. About 561 km of data along 6 lines have been recorded in this area. In the third area, on the Southern Margin of the Scotia Arc, two lines with a total amount of about 225 km have been acquired. In this area a deep crustal configuration for the streamer was used. This was the first test in which OGS used a very long streamer in Antarctic waters. The characteristics of the data acquisition system were as follows: Area 1 Area 2 Area 3 ------ ------ ------ Coverage = 3000 % 3800 % 4500 % Sample Rate = 4 ms 4 ms 4 ms Shot Interval = 50 m 25 m 50 m Streamer Length = 3000 m 1900 m 4500 m Streamer Depth = 12 m 12 m 12 m Group Interval = 25 m 25 m 25 m Number of Groups = 120 76 180 Record Length = 14 s 7 s 16 s Air-Guns: - Total Volume = 72 l 37.4 l 72 l - Pressure = 140 bar 140 bar 140 bar - Depth = 6 m 6 m 6 m

National Institute of Oceanography and Applied Geophysics - OGS, Division of Geophysics
Borgo Grotta Gigante 42/c
Sgonico (Trieste),

34010
Italy