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MULTICHANNEL REFLECTION SEISMIC DATA

All the relevant information for the acquisition is presented in the Appendix 5.1.

The seismic source was set as a tuned array of three SERCEL's GI-GUN, configured in harmonic mode, two 45+45 and one 75+75 in$^3$, towed from the starboard and port sites, respectively. The compressed air was delivered at 120-140 Bar by an electrical Mod. I25 Bauer compressor, 2500 L/m.

The array was fired and synchronized by ISMAR's 8 PORTS GUN SYNCHRONIZER MASINI1995. The RS-232 firing pulse, converted to TTL or Contact Closure by an external circuit, was provided by the PDS-2000 navigation system on programmed distances of 37.5m along the planned routes.

The seismic recording equipment employed (by Sercel) is summarized here: Seal Recording System (Sys 5), NAS drives, Esqc QA, FSK/Digimain bird controller, 96 channel Digital Streamer, 8 actives, 2 head stretches, 50 m tow leader, passive tail buoy, Digicourse cable levelers.

IMPORTANT NOTE: A fixed delay of 10ms was applied to the TB for the gun synchronization, plus 10-11 ms accounting for the opening of valves and shuttles, i.e. actual shot time is espected to appear some 20 ms after TB.

figure

Figure 6: The EEL streamer (Sercel 96 channels digital) and DIGICOURSE Cable Levelers.
\begin{figure}\epsfig{file=IMG/TIR10_PONTE_LR.eps,width=0.5\linewidth} \epsfig{file=IMG/TIR10_STREAMER_BIRDS_LR.eps,width=0.5\linewidth}\end{figure}
figure
Figure 7: GI-GUN array.
\begin{figure}\epsfig{file=IMG/GUNS_ON_DECK.PS,width=0.5\linewidth} \epsfig{file=IMG/GUNS_AT_SEA.PS,width=0.5\linewidth}\end{figure}
figure
Figure 8: Tail buoy and shot.
\begin{figure}\epsfig{file=IMG/TIR10_BUOY_LR.eps,width=0.5\linewidth} \epsfig{file=IMG/TIR10_SHOT_LR.eps,width=0.5\linewidth}\end{figure}
figure
Figure 9: Birds and Seismic Recording Acquisition.
\begin{figure}\epsfig{file=IMG/BIRD_AUX.PS,width=0.5\linewidth} \epsfig{file=IMG/SERCEL_ACQ.PS,width=0.5\linewidth}\end{figure}

next up previous contents
Next: CTD AND XBT DATA Up: MATERIALS AND METHODS Previous: NAVIGATION AND DATA ACQUISITION   Contents
2011-08-19