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2019-2020 Speakers

Prof. Sylvain Barbot
University of Southern California
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Prof. Sarah Stamps
Virginia Tech
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Prof. Jolante Van Wijk
New Mexico Institute of Mining and Technology
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From Grains to Tectonic Plate Boundaries

The cold, brittle surface of our planet continuously shakes as the giant tectonic plates that glide above a hot mantle are thrusted along, away, or towards each other. Earthquakes are the trademark of plate tectonics and the cause of many terrible disasters. Yet, the underlying physics of this global phenomenon is not clearly defined. Using insights from mechanics and numerical simulations, I will describe how the deformation of grains at the micro-scale may dictate the dynamics of large lithospheric faults and the generation of a wide spectrum of rock failures, from slow to fast earthquakes, with recurrence patterns going from repetitive to chaotic.

 


 

Clues About the Break-up of the African Continent 

The African continent is slowly fragmenting into 5 small pieces along the East African Rift System (EARS) across east Africa. What drives this process and how exactly are these pieces of Earth's crust moving? In this seminar I present data that shows how the tectonic plates of the EARS are slowly moving and deforming causing hazardous seismic and volcanic activity.  Using modern-day, high precision positioning measurements from Global Navigation Satellite Systems (GNSS) and advanced numerical modeling, we model the physics driving surface motions to understand the driving forces causing the break-up of Africa. We find that deformation is characterized by east-west extension and the major forces driving surface motions are derived from topography gradients. Deeper processes are responsible for the distribution melt beneath magma-poor rifts.


 

What Creates the Unique Topography of East Africa?

The elevation of East Africa is unusually high, commonly >3000 m above sea level. The elevation of a continent above sea level is generally related to the thick, low-density crust of the continents, plus contributions from tectonic events. In East Africa however, these two factors together cannot explain its high elevation. It has been suggested that a third component, called dynamic topography, may contribute to the high elevation in East Africa. Dynamic topography is caused by flow in Earth’s mantle.  

In this seminar, I will discuss dynamic topography, how theoretical models predict that it exists, and how we can quantify it. I will show how submarine unconformities can be used to quantify dynamic topography in oceanic basins.  

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