How does OBS data compliment/differ from land-based seismic data?
The OBS data is not quite as high quality as land data, since the OBSs cannot be carefully placed in optimum locations. They are simply dropped off by the ship and are located wherever they settle on the bottom. OBSs also have somewhat noisier signals due to currents along the ocean bottom, and in some cases the timing accuracy is not as good since the OBSs cannot receive GPS timing signals beneath the water surface. However, the OBS data is nearly as good as land data and it provides essential observations from locations where we cannot place land sensors. How long have these OBSs collected data? We installed the 58 OBSs in June, 2003 on a cruise of the Japanese research vessel R/V Kaiyo. 50 of the OBSs are from the US (built by Spahr Webb at Columbia University) and 8 of the OBSs are from Japan (built by Hajime Shiobara at the University of Tokyo). How do you retrieve the OBSs? The OBSs contain sensors that listen for sonar signals in the water. When we send them a certain code seque
