Survey Planning

BIGSETS 1998 cruise was designed to accomplish two major tasks:

1. the geological and geophysical definition of the seismogenic area offshore Cabo de Sao Vicente
2. The acquisition and the evaluation of a geophysical data set that could allow the definition of geometrical constrains to be used in tsunami modeling. MCS survey, magnetics and Sea Bottom Profiler (SBP), and the sampling of the seabed, by means of gravity piston corers were planned to achieve this goal.

The Italian and Spanish partners agreed to merge their own geophysical equipment, with the aim of optimizing the results of the cruise. Specifically the Spanish Partner made available a 48 Channel streamer and a 5000 L/Min Compressor (Hamworthy), whereas the Italian Partner made available the Seismic Source (4 Sodera GI-GUN), the 48 Channel Seismograph (Geometrics Stratavisor), magnetometer (Gem) and a 2500 L/Min compressor (Bauer). All the instrmnents came with the ancillary control equipment and spares. In addition, ship's facilities for DGPS navigation and SBP were used. A visit of UGBO members on ship Urania (end of February 1998) confirmed the feasibility of the installation of the Spanish equipment onboard, and the process for this installation was started, in particular for the accommodation of the big winch and compressors on the deck. The cruise took place from 30-oct-1998 to 9-dec-1998, with two port calls in Cartagena for mobilization and demobilization of the Spanish equipment and one port call in Portimao for the turnover of scientific crew. Hereafter, a description of the equipment and of their usage is given, along with details of the general setting and performances.