E-Mail IMAGE: Xanthippi Markenscoff is a distinguished professor in the Department of Mechanical and Aerospace Engineering at the University of California San Diego Jacobs School of Engineering. view more Credit: Xanthippi Markenscoff These mysterious earthquakes originate between 400 and 700 kilometers below the surface of the Earth and have been recorded with magnitudes up to 8.3 on the Richter scale. Xanthippi Markenscoff, a distinguished professor in the Department of Mechanical and Aerospace Engineering at the UC San Diego Jacobs School of Engineering, is the person who solved this mystery. Her paper "Volume collapse instabilities in deep earthquakes: a shear source nucleated and driven by pressure" appears in the