T44B-04
A 14-year-long Measurement of the Convergence Rate of the Juan de Fuca and North America Plates Offshore Central Oregon using GPS-Acoustics
Thursday, 17 December 2015: 16:45
104 (Moscone South)
C David Chadwell, Scripps Institution of Oceanography, La Jolla, CA, United States, Spahr C Webb, Lamont Doherty Earth Observ, Palisades, NY, United States and Scott L Nooner, University of North Carolina at Wilmington, Wilmington, NC, United States
Abstract:
The motion of the sea floor was measured at a 3000-m-deep site approximately 120 km offshore Central Oregon using the GPS-Acoustic technique in 2000, 2001, 2002, 2003 and 2014. The GPS-Acoustic derived motion relative to the interior of North America agrees with the geomagnetically-derived value within their measurement uncertainties. The time series from the early 2000’s was resurrected using two new innovations. The first innovation, a permanent benchmark that has locating channels and mating pins, allows reoccupation of an established benchmark at any later date using an ROV to replace the transponder on the benchmark. The second innovation: an autonomous platform based on a Waveglider that carries a GPS navigated acoustic transponder interrogation system that is wave and solar powered. This enables measurements to be obtained over a GPSA site without requiring a large ship, greatly reducing the cost of a GPSA measurement. Combining data at this site with data from two other GPS-Acoustic seafloor sites on the Juan de Fuca plate, makes it possible to determine a present-day Euler Pole for the Juan de Fuca – North America plates using GPS-Acoustics seafloor geodesy.
