This is an award to carry an at sea validation of a system for measuring patterns of seafloor strain accumulation with centimeter accuracy over distances of kilometers. The system is particularly suitable to ridge crest studies and will help describe the manner in which the seafloor makes the transition from episodic motion to the more or less steady state motion that is characteristic of the entire plate. The method involves the emplacement of benchmarks on the seafloor on which transponders can be placed with great accuracy. The transponders are interrogated from a towed vehicle to which is also mounted a high accuracy sound velocity meter to convert travel times to distances. Most of the equipment has been built with other funds (non-NSF); and this award grants funds for a two week experiment in the San Nicolas Basin off S. California as the first seagoing test of the apparatus. This is an important experiment because it will test a new technique for making geodetic measurements on the sea floor; the development of such techniques are an important step in understanding sea floor tectonics and evolution.
