Multichannel seismic survey sonobuoy refraction survey and ...

INTRODUCTION
This survey was undertaken as part of the Joint Programme 01 Marine Geoscientific
Research and Mineral Resources Studies of the South Pacific Region sponsored by Australia,
New Zealand and the United States of America with the cooperation of CCOP/ SOPAC. The
USGS research vessel SAMUEL P.LEE was used for this survey.
Prior to this survey, fourteen E-W and one N-S single-channel seismic reflection
profiles were acquired by CCOP /SOPAC in 1979 totaling 2140km. Also, the southern part
of the Tonga Platform was traversed by EVA III, GEORSTOM and AUSTRADEC scientific
expeditions in 1977 and 1978 organized by ORSTOM and had acquired 12 single-channel
seismic and magnetic profiles. Based on these data and the existing oil company data
available at the Ministry of Lands, Survey and Natural Resources, Nuku'alofa, Tonga, an
"Assessment of the Petroleum Potential of the southern and northern parts of the Tonga
Platform'' was prepared by CCOP/ SOPAC. This survey is the outcome of the
recommendations made in that report.
CRUISE OBJECTIVES
The objective 01 this survey was, to gather multi-channel seismic, single channel
seismic, gravity, magnetic, and sonobuoy seismic: refraction data and to dredge for rock
samples over the southern part of the Tonga Platform south of Tongatapu and 'Eua up to
approximately Longitude 23° 3D', It is envisaged that the analysis of these data will provide a
better elucidation of the sub sea-bed geology (sedimentary rocks thicknesses and structures)
and tectonics than the existing single-channel seismic data in order to assess the petroleum
potential of this portion of the southern part of the Tonga Platform.
It was also decided to gather single-channel seismic, magnetic and gravity data from
Pago Pago, American Samoa enroute to Nuku'alofa, Tonga and from around 'Eua (at the end
of multi-channel work and dredging) enroute to Suva, Fiji, in order to provide additional data
to the studies of sub sea-bed geology and tectonics of the northern part of the Tonga Platform
and Lau basin and ridge respectively.