Ongoing margin migration of Ice Stream B, Antarctica

The rate of margin migration of an ice stream can be determined using repeat measurements of the surface velocity profile within the marginal shear zone. The method relies on the assumption that the velocity profile is a characteristic feature of the margin, and that this profile is shifted laterally as the margin migrates. Application of the method to Ice Stream B, Antarctica, indicates that the southern margin is moving outward into the inland ice at a rate ofat least 9.7 ± 1.1 m a -1 .