Wide Eye Productions just wrapped up a shoot in the South Pacific on board an oceanographic research vessel.  The shoot documented a study of the Samoan Passage, a deep underwater canyon and “choke point” in the Pacific Ocean.   University of Washington Oceanographer Matthew Alford contributed this report about the voyage. You can read more of his Samoan Passage blog, here.

The display from the EM122 multibeam bathymetry mapping system. Redder colors mean shallower; bluer means deeper.

We have now completed the first part of our bathymetric survey and are working on mapping the main part of the passage.  Our first goal was to map out the western portion of our region, shown below.  This is done by sending a fan of sound beams beneath the ship and listening for the reflection of that sound off the bottom.  The travel time at each gives a “swath” of the seafloor depth that we map out as we steam along.  The previous bathymetry (seafloor topography) measurements were a patchwork of satellite gravity and an early version of our current system from 20 years ago.  The left side shows our new measurements, which we have made by steaming along the track shown in blue.  The right side shows the old measurements.  By comparing contours of where the bottom is 4300 m deep in both the old (green) and the new measurements (red), we can see the errors we are correcting.  A valley and a ridge in the old measurements disappeared – artifacts of the old data.  These are very important as they govern the path the flow takes as it makes its way through the region.