Deep-Ocean Seismometer Implantation System. Phase 1

The overall objective of this Phase I project was to determine the feasibility of a soft landing, hydraulically powered penetrator for deploying seimometers at depths of 30 to 100 meters beneath the surface of the deep-ocean bottom. Seismometers deployed at these depths will be better coupled to the sediment and will be isolated from VLFULF noise signals associated with surface waves at the sedimentwater interface and from current-induced noise. The primary application of the implantation system will be the deployment of seismometers with increased sensitivity to signals in the VLFULF band. These signals may be used in ASW activity, where ease of deployment is a primary consideration. A practical system will also be of interest to the marine seismology community. The primary objectives were to observe the penetration rate capability of a 130-mm-diameter prototype penetrator and to determine the size, logistics and cost of a complete deep-ocean deployment system. A prototype penetrator was fabricated and tested in clay bearing silt and sand. A Phase II proposal for a prototype seismometer deployment system, including cost estimates and deployment requirements, is being submitted. This system is designed to be a compact, self-contained package that can be deployed by ship or aircraft.