Free air gravity anomalies derived from radar altimetric

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

Bathymetry determined from satellite radar derived gravity plus shipboard measurements

Free Air gravity anomaly

Now consider an elastic plate which bends under the load

The flexural parameter, a where = flexural parameter

Deflection vrs x, for vertical line load on infinite plate and half plate -0. 4 p/2 0 3 p/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 Distance, x/a (a = flexural parameter 4 5

Bending of half plate F F

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

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

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

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

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

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

s o Sl pe = lu u d o m elastic 50 plastic depth, km shear stress ig r of shear strain shear stress Temperature, 1300 degrees C 0 ity id yield stress 100 shear stress shear strain ty i os ef f fo pe o Sl = co sc vi viscous fluid 150 Viscous fluid shear strain rate 200