Nemo Expedition, Legs 3
& 4
The SIO Portable Seismic
Profiling System was recently used on R/V Melville, along with the installed sub-bottom
profiler, multi-beam echosounder and gravimeter, in support of piston-coring
operations for chief scientist Nick Pisias of Oregon State University. Here are some images from that cruise;
click on an image for a larger view.
This is one of two GI guns as rigged for
towing. The black gadget is my new
High Speed Gun Float, which maintains the gun at a specified depth (in this
case, 3 meters) at up to full ship’s speed of 12+ kts.
Here
are both gun rigs being towed at about 8 kts. The guns’ shot bubbles are visible aft of the floats
Another shot of the guns in action, this
time at about 12 kts. The rig is very
stable, with minimal towing tension.
Here are some examples of profiles produced by this system. The GI gun has excellent bandwidth; recording was done at half millisecond-sampling rate, with anti-alias filtering set to 500 Hz (24 db per octave roll-off). Firing interval was 10 seconds. Where sediment exists, penetration is over a second in water depths of more than 750 meters.
- Last updated 7 July 7, 2000 -