The Smithsonian – the world’s largest research, education, and museum complex – was established by the U.S. government as a public trust 175 years ago. Many of the geoscientists working for the Smithsonian’s National Museum of Natural History (NMNH) are federal employees. The federal setting offers both challenges and opportunities to actively combat structural racism, diversify our workplace, and to increase the inclusion, representation, and celebration of BIPOC in the geosciences. Our federal affiliation affords many opportunities. Smithsonian’s widely recognized brand and mission to engage diverse audiences allows our scientists to be highly visible to the public, and representation from underrepresented communities within our ranks has the potential to inspire broader participation in the geosciences. With a large and federally supported repatriation office, NMNH is in a position to lead the decolonization of geological collections and incorporate Indigenous knowledge into our collections information. NMNH fosters strong relationships with some tribal communities that provide us with excellent resources to engage Indigenous and local scientists in our research and field work. We enjoy transparency in many federal policies on hiring, promotion, salaries and benefits, and detailed equal employment opportunity (EEO) training is required for all supervisors. Federal status also presents challenges. Progress toward diversity and equity checks are tracked at the institutional level, but do not inform individual hiring decisions. There is no legal scope for targeted hires, and actions that might increase the “yield” on offers of employment, such as making an additional position for a partner, offering perks in the form of housing, child-care, higher salary, additional benefits, etc. are prohibited by federal regulation. Several future strategies emerged as priorities in our URGE pod. We will work to (1) ensure all interns receive equitable compensation and that we advertise internship availability to underrepresented communities; (2) require applicants to provide a Diversity, Equity, and Inclusion (DEI) statement for all geoscience positions; (3) implement EEO and bias training search committee members; and (4) include DEI elements in our annual performance plans.

Estimating the melt fraction and volatile content of regions of partial melt beneath volcanoes has important implications for volcanic hazards since higher melt fraction, volatile-rich magmas are more buoyant and have a lower viscosity, and thus are more susceptible to mobilization and possibly eruption. Magnetotelluric (MT) data can be used to model subsurface bulk resistivity structures through inversion algorithms and can provide information on the distribution and amount of melt and volatiles contained in the residing magma by converting bulk resistivity to estimates of melt fraction, temperature, and water content. These are often treated as independent variables but, in reality, they are thermodynamically correlated. Thermodynamic models such as MELTS can be used to constrain the possible combinations of melt fraction, temperature, and water content such that MT interpretations are petrologically consistent. Probabilistic Bayesian inversion that incorporates these constraints can be used to find a distribution of models and interpretations which fit the MT data and provide a better understanding of the uncertainty in MT-derived estimates of melt fraction. In this study, we apply MELTS-coupled 1-D Bayesian inversions of MT data at Uturuncu Volcano to evaluate the constraints that MT data can provide on melt fraction estimates. Uturuncu Volcano is a large composite volcano in southern Bolivia at the center of the Altiplano Puna Volcanic Complex (APVC), the result of a large ignimbrite flare-up during the past 10 Ma. Previous geophysical studies have shown that the APVC is underlain by the voluminous, laterally-extensive Altiplano Puna Magma Body (APMB) at approximately 15-20 km depth below surface. The APMB has previously been interpreted to have a wide range of melt fractions anywhere from 4% to 45%, but MT results suggest anomalously high water contents of up to 10 wt%. Initial results from petrologically-consistent MT inversion modelling suggests that the resulting low resistivity of the APMB beneath Uturuncu requires high melt fractions (e.g. >90%) in near-saturated conditions. This suggests that either high melt fraction near-saturated magma reservoirs exist at depth or that a significant phase of saline fluids in over-saturated low melt fraction conditions is present.