Crustal and upper mantle structure beneath Antarctica and surrounding oceans

• Main Authors: Michael H. Ritzwoller, Nikolai M. Shapiro, Anatoli L. Levshin, Garrett M. Leahy
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2001
• Subjects: West Antarctica; The Corridor; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.228.9397; http://ciei.colorado.edu/geophysics/pubs/mhrpubs/pubs/2001/12.pdf

We present and discuss a new model of the crust and upper mantle at high southern latitudes that is produced from a large, new data set of fundamental mode surface wave dispersion measurements. The inversion for a 2 ° 2 ° shear velocity model breaks into two principal steps: first, surface wave tomography in which dispersion maps are produced for a discrete set of periods for each wave type (Rayleigh group velocity, 18–175 s; Love group velocity, 20–150 s; Rayleigh and Love phase velocity, 40–150 s) and, second, inversion for a shear velocity model. In the first step, we estimate average resolution at high southern latitudes to be about 600 km for Rayleigh waves and 700 km for Love waves. The second step is a multistage process that culminates in a Monte Carlo inversion yielding an ensemble of acceptable models at each spatial node. The middle of the ensemble (median model) together with the half width of the corridor defined by the ensemble summarize the results of the inversion. The median model fits the dispersion maps at about the measurement error (group velocities, 20–25 m/s; phase velocities, 10–15 m/s) and the dispersion data themselves at about twice the measurement error. We refer to the features that appear in every member of the ensemble as ‘‘persistent.’ ’ Some of persistent features are the following: (1) Crustal thickness averages 27 km in West Antarctica and 40 km in East