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USGS Coastal and Marine Geology Program

Field Activity Details for field activity 1987-042-FA

Other ID: STRL S8-87-AFR

Status: Completed

Organization(s): USGS, Woods Hole Coastal and Marine Science Center

Funding Program(s):

Principal Investigator(s): Catherine Delorey

Affiliate Investigator(s):

Information Specialist(s): Catherine Delorey

Data Type(s): Electro-Magnetic: Gravity, Sonar: Single Beam, Electro-Magnetic: Magnetics, Location-Elevation: Navigation

Scientific Purpose/Goals: Collect gravity, magnetics and bathymetric data in and around the waters of Equatorial Guinea and Gabon as specified by DMA requirements.


Start Port/Location: Douala, Cameroon

End Port/Location: Abidjan, Cote d'Ivoire

Start Date: 1987-10-22

End Date: 1987-11-04

Equipment Used: GPS (wh), 12 kHz, LaCoste-Romberg gravimeter G-179, Geometrics G-856 magnetometer, Gyro compass, GE 810 Correlation sonar

Information to be Derived:

Summary of Activity and Data Gathered: The ship departed Doula and proceeded to surops area on 22 Oct. 1987. Upon completion of lines begun on previous leg S7-87-AFR in the waters off Gabon, the ship headed northward to complete lines off Equatorial Guinea. Several lines in both survey areas were shortened on landward end due to shoals. The presence of oil rigs required further adjustments of lines in both regions. Surveying was completed on 31 Oct. 1987 followed by a three-day transit to Abidjan where the ship docked on 4 Nov. 1987. Final gravity land ties were completed in Abidjan on 5 Nov. to tie ship meter data with a known gravity station and to verify the accuracy of two previous land ties performed in the same area.

Staff: Catherine Delorey, Carol A. Ryland

Affiliate Staff:
Linda Sheetz; William Wright - USGS

Notes: Original Center People field contained: Catherine Delorey - Ch. Sci., Carol Renaud, Linda Sheetz.
Project = Defense Mapping Agency Gravity, Defense Mapping Agency Gravity


Gabon, Equatorial Guinea, Africa, North Atlantic, South Atlantic;

North: 4.5 South: 3.5 West: 8 East: 11


photo of Starella


Folger, D.W., McCullough, James R., Irwin, Barry J., Driscoll, George R., Delorey, Catherine M., and Polloni, Christopher F., 1990, Map showing free-air gravity anomalies off the western coast of Africa; Nigeria to Gabon: U.S. Geological Survey Miscellaneous Field Studies Map MF-2098-F, scale 1:1,500,000.


Data Acquired

Survey EquipmentSurvey InfoData Type(s)Data Collected
LaCoste-Romberg gravimeter G-179 --- Gravity
12 kHz --- Single Beam
1987-042-FA-SE-001 ( Collection of paper record displays of seismic data (12K) for lines )
Geometrics G-856 magnetometer --- Magnetics
GE 810 Correlation sonar --- Navigation
Gyro compass --- Navigation
GPS (wh) --- Navigation

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