# Phoebe Robinson

• Program Year: 2
• Practicum(s):
Lawrence Berkeley National Laboratory (2012)
• Degree(s):
Mphil Polar Studies, Cambridge University, 11/2010; B.A. Applied Mathematics, Harvard College, 6/2009
• Field of Study: Earth Science

### Summary of Research:

A tectonically complex fault network extends across the western United States, which is home to 70 million people. It is therefore of utmost humanitarian importance to understand fault interactions within this network to better assess seismic hazards. In my research, I plan to use Boundary Element Method (BEM) models to examine the predicted slip distributions on both mapped and fractal fault systems that span the range of complexity that likely exists in active fault systems. BEM models will provide insight into fundamental questions about how multiple faults interact and terminate.

In our BEM models, fault surfaces are discretized into triangular dislocation elements in a linear elastic half-space. The slip vectors on each dislocation element can be related to the resolved shear stresses on all other elements as s = Gm, where s represents the regional shear stresses resolved onto each of the dislocation elements, m represents the unknown slips on each dislocation element, and G is a matrix of partial derivatives derived from elastic dislocation theory.

This problem is computationally challenging because high-resolution representations of observed or hypothesized fault system geometries require hundreds of thousands to millions of elastic dislocation elements. BEM models involve large inverse problems, but it is matrix assembly rather than inversion that is rate-limiting. The Green’s functions for individual triangular dislocation elements in a homogeneous elastic half-space involve calculations of stresses from six angular dislocations, involving thousands of arithmetic and trigonometric operations. To do these calculations, I am going to explore parallelization – which will likely be my central focus – and perhaps also graphics processing unit (GPU) acceleration.

### Publications:

Robinson, P.M. and J. A. Dowdeswell, 2011. Submarine landforms and the behavior of a surging ice cap since the last glacial maximum: The open-marine setting of eastern Austfonna, Svalbard. Marine Geology, Vol. 286 (1-4), p. 82-94.

DeVries, P.M.R. and B.J. Meade, 2012. Earthquake cycle deformation in the Tibetan plateau with a weak mid-crustal layer, Manuscript submitted for publication to the Journal of Geophysical Research - Solid Earth.

### Awards:

Cambridge University, Emmanuel College, Masters of Philosophy in Polar Studies with Distinction, 2010.

Hershel Smith Fellowship Winner, a fellowship funding my year of postgraduate study at Cambridge University, 2009-2010.

Harvard University, Graduated Magna Cum Laude, 2009. B.A. in Applied Mathematics with an application field of Earth and Planetary Sciences. GPA: 3.86.

Phi Beta Kappa, Inducted 2009.

Received Highest Honors for Senior Thesis entitled “An Analysis of the 1996, 2002 and 2007 Boso Peninsula Slow Slip Events.”

Rhodes Scholarship finalist, Massachusetts and New Jersey District, 2008.

Marie L. Rose Scholarship awarded for academic excellence by the Huguenot Society of America, 2007-2009.

College Rowing Coaches Association Scholar-Athlete Honors, awarded by the National Collegiate Athletic Association (NCAA) to athletes who excel both athletically and academically, 2007, 2008, and 2009.

Detur Prize Winner for Outstanding Academic Achievement, a prize for finishing in the top 5% of the freshman class at Harvard University, 2006.

John Harvard Scholarship, awarded for academic excellence by Harvard University, 2005-2006.