Question: In your Ph.D what are you doing a thesis on?

Hannah Bentham answered on 25 Jun 2013:

My thesis is on using earthquakes to look for alterations in the Earth’s interior. These alterations come from oceanic crust being subducted at convergent boundaries. But the crust is not destroyed – it gets pushed down deep into the Earth. In the past we have struggled to image what happens to this subducted crust, but we know it arrives back to the surface of the Earth in lavas in places like Hawaii.

The earthquakes I use are from SE Asia and I look at the energy that arrives at seismic stations in North America. The great thing is: I can comfortably download the earthquake data from the internet, even while chilling out on my sofa! I use the data so I can create images of what lies 1000s of km (1000000 meters) beneath our feet, in the depths of the Earth. Luckily the methods I use are similar to those that create the X-ray or CAT scans that you might get in a hospital, so are standard imaging techniques.

I generally look for subducted ocean crust and in my recent work I have found oceanic rock that could be from 80 million years ago. Now that’s pretty old! These old rocks are important because they help us understand plate tectonics, today and in the past, and also how convection in the Earth is connected to the changing world on the surface.