Corné Kreemer, and William Holt (SUNY Stony Brook)
Paper in GRL is available hereWe investigate possible driving forces behind the occurrence of the 1998 Antarctic plate earthquake. We determine first a regional strain rate field associated with the accommodation of relative plate motion, and second, a vertically averaged minimum deviatoric stress field associated with lithospheric gravitational potential energy differences and deglaciation of the Antarctic ice cap. We find that the mechanism of this event is inconsistent with strain orientations inferred from kinematic modeling of a diffuse zone of deformation within the triple junction region. Stress perturbations associated with deglaciation cannot be ruled out as a triggering mechanism for this event.
Figure 2. a) Grid in which a strain rate field is determined associated with the accommodation of relative plate motions [DeMets et al., 1994]. These motions are applied as boundary velocity conditions, illustrated by the grey arrows.
Figure 3. a) Principal axes of the vertically averaged minimum horizontal deviatoric stress field caused by gravitational potential energy differences within the lithosphere. CMT focal mechanism of Antarctic plate earthquake is shown. a) 'ice-age' simulation. b) change in stress tensor field from 'ice-age' to present day determined by taking the tensorial difference between the two solutions.