Scotia arc kinematics from GPS geodesy

Abstract

GPS crustal velocity data from the Scotia and South Sandwich plates, transform azimuths, spreading data, and an updated earthquake slip vector catalog provide the first Scotia and South Sandwich plate Euler vector estimates not dependent on closure as the GPS data tie them to the global plate circuit. Neither the GPS data, which sample limited portions of the plates, nor the geologic data, which are not tied to the global spreading circuit, are sufficient individually to define the Euler vectors. As Scotia plate GPS measurements do not sample the stable plate interior, plate boundary deformation field modeling is necessary for Euler vector estimation. Our South America-Antarctic and Scotia-South Sandwich Euler pole estimates agree with previous estimates from either GPS or geologic data. Our South America-Scotia Euler vector, however, is significantly different and near the South America-Antarctic Euler vector producing an approximately coaxial motion of Scotia between South America and Antarctica. Copyright 2007 by the American Geophysical Union.