Outward Driving Force due to Isosta4cally Compensated Topography -­‐  ver&cal force balance -­‐  isosta&c thickness vs. seismic thickness -­‐  horizontal force balance -­‐  outward driving force of Tibet w.r.t India -­‐  collapse of Larsen-­‐B ice sheet h?p://en.wikipedia.org/wiki/Larsen_Ice_Shelf#mediaviewer/File:Larsen_B_Collapse.jpg h?p://www.eas.slu.edu/People/LZhu/research/&bet/intro.html h?p://www.eas.slu.edu/People/LZhu/research/&bet/intro.html Airy Isostasy for Plateaus and Con4nents [Schubert and Sandwell, EPSL, 1989] Airy Isostasy for Plateaus and Con4nents [Schubert and Sandwell, EPSL, 1989] Outward Driving Force due to Isosta4cally Compensated Topography -­‐  ver&cal force balance -­‐  isosta&c thickness vs. seismic thickness -­‐  horizontal force balance -­‐  outward driving force of Tibet w.r.t India -­‐  collapse of Larsen-­‐B ice sheet h?p://en.wikipedia.org/wiki/Larsen_Ice_Shelf#mediaviewer/File:Larsen_B_Collapse.jpg h?p://topex.ucsd.edu/geodynamics/16_Transfer.pdf h?p://topex.ucsd.edu/geodynamics/16_Transfer.pdf Exercises 1)  Compute the average outward stress of Tibet (62 km thick crust) rela&ve to India (35 km thick crust). Use crustal and mantle densi&es of 2700 kg/m^3 and 3200 kg/m^3 respec&vely. (a) Use isostasy to calculate the total thickness of the crust under Tibet. (b) Use the integral derived in class to calculate the total outward force per length. Divide by the thickness of the Tibet crust to get the average stress. 2)  Collapse of Larson Ice Shelf -­‐ Between January and march of 2002 the Larson B ice shelf disintegrated. The area of the shelf was about equal to the size of Rhode Island. Calculate the average outward stress in a 220 m thick floa&ng ice shelf having a density of 960 kg/m^3. (a) Use isostasy to calculate the ice freeboard. (b) Use the integral derived in class to calculate the total outward force per length. Divide by the thickness of the ice to get the average stress.