Free air gravity anomalies derived from radar altimetric determinations of geoid height

1. Free air gravity anomalies derived from radar altimetric determinations of geoid height milligals

2. Bathymetry determined from satellite radar derived gravity plus shipboard measurements

5. Free Air gravity anomaly

8. Now consider an elastic plate which bends under the load

9. The flexural parameter, a where = flexural parameter

10. Deflection vrs x, for vertical line load on infinite plate and half plate -0.4 p/2 0 3p/4 0.4 Infinite plate, vertical line load at x =0 0.8 1.2 Half plate, vertical line load on edge 1.6 2.0 0 1 2 3 4 5 Distance, x/a (a = flexural parameter

11. Bending of half plate F F

12. Outer (oceanic side) slope of trenches associated with subduction zones elastic plate model elastic-plastic model

13. Outer (oceanic side) slope of trenches associated with subduction zones elastic plate model elastic-plastic model plastic stress elastic strain

14. Venus Gravity, Topography and Geoid High correlation between gravity and topography Anomaly amplitude similar to Earth Data from Magellan spacecraft, Images from Wieczorek, 2006

15. Free air gravity anomaly from Mars Global Surveyor (MGS) Mars Gravity & Topography Maps • Total amplitude of anomaly larger than on Earth Why? Mars topography from MOLA on MGS

16. Elysium volcano Gravity anomalies from Martian features •From Goddard Space Flight Center Gravity maps Isidis impact crater

17. Gravity data from lunar nearside from Lunar Prospector (Sugano and Heki, 2004) Topography data from Clementine LunarGravity & Topography Maps • Again total amplitude of free-air anomaly larger than on Earth Global map from Knopoliv et al., 1998

18. 1300 Temperature, degrees C 0 elastic shear stress Slope = modulus of rigidity elastic 50 shear strain plastic depth, km plastic shear stress yield stress 100 shear strain 150 viscous fluid shear stress Slope = coeff of viscosity Viscous fluid shear strain rate 200