We acquired a total of 
2715 Km of 48 Multichannel Seismic Data (fig. 4),
with CDP coverage ranging from 2400 to 1200%, along
with bathymetry, SBP and magnetics. Two lines were shot with a coverage
600% every 100 m for reflection and refraction purposes.
After an aproximate 2 days initial phase for balancing the streamer and
resolving installation problems with the streamer and gun array, the geophysical data acquisition
was performed smoothly and continuously during the entire first leg.
Some leakage and noise
problems on some traces persisted up to the end. The GI-GUN lived up to its
name for repeatability and performed reliably, except for very
short periods, owing to some overcharging of the 2500 L compressor at
abnormally high vessel speed.
The Multichannel data processed on board revealed reflectors down to the acoustic basament, even with one single gun, with resolution from acceptable to very good, thus confirming the capabilities of well tuned, very small GI-GUN arrays.
The digitized bathymetric data was acceptable for more than 85 % of the acquisitions, and will need some postprocessing for cleanups.
Magnetic recordings showed an oustanding continuity of data and lack of spikes, requiring just a minimal pass for filtering. One line shows some features that, while awaiting land based observatory data, can be probably related to a storm. Once the observatory data is available, the data will be cleaned for diurnal variations and IGRF corrections will be applied. An example of the acquired magnetic data data is presented on Fig. 5.
The elastic bulk parameters of the studied area will be hopefully estimated from the refraction data acquired (lines BSO6, BS07A, BS26) and from the foreseen Ocean bottom Seismograph (OBS) and deep penetrating surveys, (the OBS survey would furnish also natural seismic activity, source depth and the eventual motion of the sea bottom during earthquake). The local gravitational field can be obtained from available satellite data (Sandwell et al.,1996)
The data collected during the MCS and SBP surveys would allow the evaluation and the test of both body force approach and linear approach for the above mentioned reasons.
The MCS survey imaged well enough the structural features, like length of a portion of rupture, fault dip, length, rupture direction etc. of the explored area and the SBP survey were able to detect the fault and the free face fault displacement. The long pattern fault detected during this survey, together with the foreseen high resolution bathymetric survey and the OBS survey may furnish the major elements to an accurate tsunami modeling, regarding both generation and arrival zones, and hopefully early warning.
We collected a very interesting and complete geophysical and geological data set.
Ship Urania performed well and all the heavy geophysical equipment were quit easily allocated and operated on the deck, thus demonstrating the feasability of sharing equipment and personnel for heavy seismic cruises.
The Italian, Spanish and Portugese teams worked together in good harmony, and, finally, the work onboard was performed smoothly without significant equipment problems, with no personnel or environmental problems, and in perfect agreement with the ship's officers and crew.
