FY 1994

Acoustic Extensometer: A precise low-cost array for horizontal deformation monitoring on the sea floor

Meinig, C., H. Milburn, R. Newman, and W. Chadwick

In Oceans '93, Engineering in Harmony with the Ocean, Proceedings, Vol. II, Victoria, B.C., Canada, 18–21 October 1993, 117–121 (1993)

A new seafloor instrument array has been designed for high-resolution acoustic measurements of horizontal deformation along active mid-ocean spreading centers over a short baseline (<1 km). Distances are measured by the round trip travel time of 50 kHz bursts between adjacent instruments, which are microprocessor controlled. The array consists of a minimum of two instruments, but can be enlarged to greater lengths by adding units. The system can be deployed for up to 1 year from a surface ship, submersible, or Remotely Operated Vehicle (ROV). Signal round trip travel time, temperature, and attitude are measured at software-controlled intervals. Preliminary results indicate the calibrated system precision is within 1 cm over a distance of 600 m.