25 January, 2004
Day two without ice, and it is a cold gray day. Visibility is poor and we are running with seismic streamer all day today. The fog has moved in and we have had snow most of the morning. The decks are white, but there is very little cheer on the Palmer. The change in weather has made everyone a bit quieter today. Doing the marine mammal observing is parcticularly difficult with the low visibility. The wind has started to pick up so the swells are often white capped. When we are looking for whales, we look for the spray from the blowholes. In calm seas these are much easier to distinguish.
We have six guns in the water and seismic is the order of the day. We are currently in the open water to the east of B15A making transits of 40 nautical miles or more before we turn to establish a new shot line. Along these lines we hope to locate faults and volcanic formations. By making parallel lines to one another, the scientists can orient the direction of these features relative to one another. They can extrapolate a fault's direction to points beyond the collected data to estimate the direction that it takes on the Antarctic Continent and out into the ocean.
When we are taking seismic data the watch goes much more quickly. We have to log longitude and latitude, sea floor depth, ship speed, ship direction, magnetic data, gravity data and shot point every five minutes. Every fifteen minutes we also have to record shot point, and confirm that the data collection for the multichannel streamer is operating properly. At thirty minute intervals, we have to record longitude, latitude, and shot point on a real-time graph of the seismic data. Every hour we rotate between watch station, marine mammal observation and beam editing. The variety does make the time go faster.
Stuart Henrys and Huw Horgan have been working with electronic techs and marine techs to insure that we are collecting the best data possible. With their help and that of Mark Weiderspahn, UTIG, they have been working to identify any problems that would contribute to "bad" data. "Bad" data points are present in all data collected, but through thorough analysis, the affect of these points is minimized in the final analysis.
The scientists are always looking over the preliminary data, trying to identify trends and features that will help them to understand the nature of the crust. When they find promising data, they use specialized computer programs to re-graph the data to allow them to identify subtle variations that are much more difficult to see in the initial plotting.
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