Elvira Mulyukova, Ph.D.

My academic interests revolve around the general question of ‘How do terrestrial planets form and evolve?’ Specifically, my research is aimed at understanding the physical processes, ranging from the atomic scale of rock crystals and to the planetary scale of mantle convection, that control thermal and compositional evolution of a planet. Up to now, our home planet Earth has been the focus of my work, since it is the most accessible in terms of observational data with which to constrain physical models, and, not least, since it is the most relevant for human life. However, my larger goal is to develop physical models that are not limited to Earth, but can be applied to other terrestrial planets in our Solar system and beyond.

In my current work as a Post-Doctoral Associate at the Department of Geology and Geophysics at Yale University, I use my background in physics, continuum mechanics and geodynamics to develop analytical models of lithospheric deformation. The goal is to understand the self-weakening mechanisms that allow for strain localization to occur. This process plays a crucial role in the formation of plate boundaries – a unique and enigmatic feature of the plate tectonics on Earth. By constantly bringing new mantle material to the surface, plate tectonics affects the chemistry of the ocean and atmosphere, and thus also the long-term climate stability and the biological evolution. Understanding plate tectonics is thus a fundamental step towards understanding the Earth system as a whole.

While my main background is in physics, some of my research has been carried out at cross-disciplinary institutions, aimed at bridging Physics, Earth and Mathematical Sciences. During graduate studies, the interdisciplinary approach proved to be highly beneficial for my work on Earth’s thermochemical evolution, where I developed a numerical code for long-term simulation of mantle convection, and linked the resulting models with the geological record, mineral physics data, seismic tomography models, and geochemical observations.

Some of the current frontiers in planetary and geophysical sciences that I find the most exciting can be summarized in the following questions:

1. What are the physical mechanisms that allow for plate tectonics to exist on Earth?

Plate tectonics is the surface manifestation of convective mantle flow. While other planets, such as Mars and Venus, are also thought to cool via mantle convection, Earth is the only known terrestrial planet with a mobile lithosphere that exchanges volatiles and minerals with the surface, which is possibly a necessary condition for long-term temperate climate and habitability.

In order for a new tectonic plate to form, the cold and stiff oceanic lithosphere must be weakened sufficiently to deform at tectonic rates. Such rates are especially hard to attain in its cold ductile portion, where the lithosphere reaches its peak strength. Ultimately, the mechanism that enables lithospheric weakening is responsible for Earth’s tectonic mode of mantle convection, which would otherwise proceed in a stagnant lid regime, as is the case on Venus.

In one of my recent projects, I tested the hypothesis of spontaneous subduction initiation via the collapse of a passive margin, which is a prime example of formation of a new tectonic plate boundary. I applied the microphysical theory of two-phase grain damage to demonstrate that lithospheric stiffening due to cooling can be offset by weakening due to rapid grain size reduction, and thus enable the collapse of a passive margin.

2. What are the building blocks of terrestrial planets?

Some of the most important parameters that enter geodynamic models, and which determine their validity and interpretation, are derived from our understanding of the Earth’s compositional building blocks. Terrestrial planets are thought to form by collision and accretion of planetesimals, which are potentially similar to the rocky and/or metallic objects that constitute the main asteroid belt between Mars and Jupiter. I am currently a member of the scientific team whose mission is to send a spacecraft to the asteroid Psyche, which is hypothesized to be an exposed nickel-iron core of an early planet, one of the building blocks of our solar system. As part of this project, I am building a theoretical model of flow in a porous medium in the presence of a magnetic field; this model can be used to understand the process of crystallization of this asteroid, as well as that of Earth’s core and the cores of the other terrestrial (rocky) planets.