Seismology 101
Sometimes it's ok to make waves
The face of the Mertz glacier from the bow.
After crossing the sea ice, we made it to the edge of the Mertz glacier. We have 2 days to do science. A LOT of science! After that we must cross the sea ice again and head to the Totten. (Are you following the ships route?) This will take 3-4 days. During our time at the Mertz we gathered biotic and abiotic specimens from the sea floor and plankton from the water. I'll show you and discuss those later. We gathered physical oceanographic data using ctd's and uctd's and observed marine mammals from the bridge and recorded their behaviors. Later on those also. Let's talk Seismology. The branch of science that use bouncing sound waves to create images.
An image of the ocean floor using the multibeam.
If you have ever used a fish finder to catch a fish or had an ultrasound, seismology is the same thing except it images the earth.
We have 3 types of seismic equipment on board. The first one is the mutlibeam. It is used to give an image of the ocean floors topography, as you can see above. The second is a CHIRP system. It is like a really good fish finder.
An image from the CHIRP.
Simply put the mutlibeam gives a general image of the ocean floor. The CHIRP penetrates the sea floor 10' of meters and gives excellent detail. This will be important when we need to dredge for rocks or core sample for sediment. It is critical that the rocks and sediments we gather are from the correct geologic time. We are particularly interested in the time frame where the Eocene and Oligocene transition as these are times of historical sea ice change. Confusing? Be patient I'll explain that later also.
Deploying a seismic streamer from the stern.
Then there's the big gun! Literally! The seismic streamer. This device consists of a long cable and high pressure guns (under the orange buoys). The guns release a powerful blast of high pressure creating a large bang. These sounds waves can penetrate much deeper into the ocean floor, giving valuable details of sub bottom layers. These help determine geologic time.
Processing the information in the dry lab.
All this information is then carefully analyzed and recorded. The data gathered will help with the science on this cruise and for future research. Remember we are in uncharted waters where no data exists, so it is invaluable. Tomorrow our Transit to the Totten begins. I hope the seas are calm!
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