David Stegman, PhD

Dave Stegman is a Professor of Geophysics in the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics at Scripps Institution of Oceanography at

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UC San Diego. A driving curiosity of his research is "Why is Plate Tectonics unique to Earth?" To address this, Dr. Stegman uses high-performance computing and numerical simulations to investigate the dynamics of planetary interiors and the long term evolution of planetary tectonics, volcanism, and magnetic field generation. He has published numerous studies in Science and Nature, as well as many other top venues of his field, on topics relating to Earth, Venus, Mars, and the Saturnian moon Enceladus. His research has been supported by NASA, the Dept of Energy, Office of Naval Research, and the National Science Foundation, which included an NSF CAREER award in 2013. Prior to joining UC San Diego, he was the Centenary Research Fellow at the University of Melbourne and an ARC Australian Postdoctoral Research Fellow at Monash University. He graduated from Bowdoin College with a degree in Physics before he received his PhD from UC Berkeley.

Sharp Minds July 1, 2024 Lecture Topic

How the Indian Continent Broke the ‘tectonic speed limit!’

During the Cretaceous Period, the Indian plate moved towards Eurasia at some of the fastest speeds ever recorded (up to 21 cm per year!). Scientists were very puzzled by this because the typical forces that drive tectonic plate motions can only achieve speeds of about 7 cm/yr. I will describe the details of this journey, as they are preserved in the rocks of the Indian Ocean seafloor, and document two distinct pulses of fast motion, separated by a noticeable slowdown. The first, and largest, of these two bursts of speed occurred around 70--65 million years ago, just before an asteroid collided with Earth that led to the global extinction of the dinosaurs. To investigate this mysterious connection, my team developed computer simulations of the Earth's deep interior that describe how surface plate motions are driven by events deeper in the mantle. Our models explain these enigmatic plate motions by hypothesizing a previously undocumented tectonic plate existed to the north of the Indian plate, which was completely consumed by 43 Million years ago. This marked the end of the Indian plate's northward journey, as continental India started colliding with Eurasia to begin producing the largest mountain range on Earth – the Himalayas.