IGPP is pleased to invite you to join its Spring 2022 Seminar Series presentation featuring University of Connecticut's Vernon F. Cormier. Dr. Cormier's talk, "Mantle Phase Change Detection from Stochastic Tomography" will be available IN PERSON and via Zoom on MONDAY, May 2, 2022, starting at 12:00pm. Zoom: https://ucsd.zoom.us/j/91591303159?pwd=dDdSb3hqbVhXem83SVE0Tnc2aXgvQT09. Password: mantle
Time: 12:00 pm, Pacific Time
Note: This meeting will be recorded. Please make sure that you are comfortable with this before registering.
Abstract: Stochastic tomography, made possible by dense deployments of seismic sensors, is used to identify previously undetected and poorly detected changes in the composition and mineral structure of Earth’s mantle. This technique inverts the spatial coherence of amplitudes and travel times of body waves to determine the depth and lateral dependence of the spatial spectrum of seismic velocity. This spectrum can be predicted from the thermodynamic stability of different compositions and mineral phases as a function of temperature and pressure. The spectrum predicted by thermodynamic models of a pyrolitic mantle, for example, is characterized by peaks in the fluctuation of seismic velocity in narrow ranges of depth. These peaks closely match those found from applying stochastic tomography to elements of Earthscope and FLEX arrays above the western US The interpretation of this heterogeneity spectrum (Figure 1) will enable new constraints to be found on the history of tectonic plate subduction beneath North America and the compositional component of crustal and tectonic plate fragments that have been cycled through Earth’s mantle.