Jonathan Boon Viva presentation 19 th June 2007 Level Set Methods for Multilayer Geological Folding Supervised by Prof. C. Budd & Prof. G. Hunt

2 Motivating Example

3 Experiments

4 Model 1 Euler Energy Critical Load depends on length of strut.

5 Model 2 Strut on a linear elastic foundation – more realistic Critical load Wavelength

6 Model 3 Viscous foundation Biot: Dominant wavelength Valid for small deflections. Wavelength does not agree well with reality.

7 Multilayer models Two layer model developed (Budd et al. 2003). Addition of friction to elastic foundation model. Can not accurately extend to n layer model because outer layers become non- sinusoidal… Use level set method to model the multilayer geometry.

8 LSM applied to parallel fold

9 Comparison of model with experiment Reformulate mechanical model in terms of the geometry

10 Conclusion Singularity formation in multilayers can be predicted by the geometry. Nonlinear bending energy provides a mechanism of restabilising a fold. Serial folds form most naturally from the reactive end. Further work needed to verify results and to check the effects of unmodelled behaviour such as shakedown.