The map below shows the location of ocean bottom seismometers (OBSs) that we have deployed since leaving port on October 23. These instruments will sit on the seafloor until the end of November, while we generate small seismic sources in a grid above them. The data from this experiment will be used to construct an image of the earth’s crust beneath the seafloor. The instrumentation and the scientific background for this experiment will be discussed in upcoming posts. Fifty of the OBSs are being supplied by the Scripps Institution of Oceanography in La Jolla, California, as part of the U.S. Ocean Bottom Seismic Instrument Program (OBSIP). Nineteen are being supplied by GEOMAR, in Germany. Fourteen of these were recovered from the seafloor after being there for the past year recording aftershocks of the April 1, 2014 Iquique earthquake.