Reflection seismic, magnetic, gravimetric survey in the Ross Sea, Antarctica (Summer 1987-88, 88-89, 89-90, 90-91)

During the Antarctic summers from 1987 - 1988 to 1990 - 1991,
the Osservatorio Geofisico Sperimentale realized a geophysical survey
in the Ross Sea, making use of the Research Vessel OGS - Explora,
collecting magnetic, gravimetric and seismic data. This research has
been carried out in the context of the Nation Research Program in
Antarctic (PNRA), coordinated by the Italian ENEA, under the auspices
of the Italian Ministry for Scientific and Technological Research.

The parameters for the different campaign are:

Period from 25th January to 8th March 1988:

a total of 2,323 km of multichannel seismic lines has been
collected. One of the seismic lines has been recorded at 4 ms sampling
rate, shooting every 75 m and recording over 24 sec to obtain
information on the deepest layers of the earth's crust. The data have
been obtained with the following parameters:

Coverage 2400%
Record Length 12 sec
Sample Rate 2 ms
Shot Interval 50 m
Streamer Length 2400 m
Streamer Depth 12 m
Number of Groups 96
Group Interval 25 m
Air-Guns:
- Total Volume 46.16 1
- Pressure 140 bar
- Depth 6 m

Summer 1988 -1989:

in the South Pacific Ocean and in the Ross Sea areas a total of 4,202
km of reflection seismic profiles and 17 refraction datasets have been
acquired. The data have been collected with the following parameters:

Coverage 3000%
Record Length 14 sec
Sample Rate 4 ms
Shot Interval 50 m
Streamer Length 3000 m
Streamer Depth 12 m
Number of Groups 120
Group Interval 25 m
Air-Guns:
- Total Volume 45.16 1
- Pressure 140 bar
- Depth 6 m

Summer 1989-90:

The survey interested three different areas: the Antarctic Peninsula,
the South Pacific Ocean and the Ross Sea where a total of about 2,600
km of seismic profiles have been acquired with the following
parameters:

Coverage 3000%
Record Lengtht 14 sec
Sample Rate 4 ms
Shot Interval 50 m
Streamer Length 3000 m
Streamer Depth 12 m
Number of Groups 120
Group Interval 25 m
Air-Guns:
- Total Volume 45.16 1
- Pressure 140 bar
- Depth 6 m

Data have also been acquired in fours sites of particular
interest, where the acquisition parameters have been modified as
follow:

Coverage 6000%
Record Length 6 sec
Sample Rate 2 ms
Shot Interval 25 m
Streamer Length 3000 m
Streamer Depth 12 m
Number of Groups 120
Group Interval 25 m
Air-Guns:
- Total Volume 22,5 1
- Pressure 140 bar
- Depth 6 m

Finally, some refraction sesimic profiles have been acquired
in cooperation with the United States Geological Survey (USGS).

December 1990, January, February and March 1991:

total of 557 km of deep seismic, gravity and magnetic data have been
collected with the following parameters:

Coverage 3000%
Record Length 14 sec
Sample Rate 4 ms
Shot Interval 50 m
Streamer Length 3000 m
Streamer Depth 12 m
Number of Groups 120
Group Interval 25 m
Air-Guns:
- Total Volume 45.16 1
- Pressure 140 bar
- Depth 6 m

Source Name:Research Vessel > OGS-Explora

Sensor Name:ASTR1>Analogic streamer, Prakla
Sensor Name:MSREC1>Multichannel seismic recorder,Sercel 358
Sensor Name:GMG1>Magnetometer Geometrics, G801-803
Sensor Name:BGV2>Gravimetric Bodenseewerk, KSS31