On some Langseth expeditions, seismometers are lowered to the ocean floor–here, off southern Alaska, where another great earthquake zone lies. The seismometer will record sound waves released by the ship, allowing scientists to image earth’s deep structures. http://blogs.ei.columbia.edu/2012/07/09/investigating-the-world%E2%80%99s-oceans-pole-to-pole-and-deep-below-the-bottom/
