2016 James B. Macelwane Medal Winner
Maureen D. Long was awarded the 2016 James B. Macelwane Medal at the AGU Fall Meeting Honors Ceremony, held on 14 December 2016 in San Francisco, Calif. The medal is for “significant contributions to the geophysical sciences by an outstanding early-career scientist.”
Maureen Long has made seminal contributions to our understanding of circulation in the Earth’s mantle by combining seismology, mineral physics, and geodynamics. Much of Maureen’s work concerns subduction zones, which are delineated by deep ocean trenches, where tectonic plates sink, or subduct into the Earth’s mantle. The direction of mantle flow driven by convection, plate motion, and sinking slabs is best detected with seismic anisotropy that is caused by deformation-induced fabric in minerals. Maureen Long is a pioneer and leader in using seismic anisotropy to reveal how slabs subduct and the mantle circulates.
For her graduate work at the Massachusetts Institute of Technology, Maureen combined seismic observations with numerical models and mineralogical experiments to study anisotropy beneath Japan. With her multidisciplinary tool kit, she then began her major research thrust on subduction zones, first as a postdoctoral fellow at the Carnegie Institution of Washington’s Department of Terrestrial Magnetism and later as a faculty member at Yale. Maureen led or co-led seismological field deployments in Oregon, the Appalachians, and Peru and an oceanographic survey over the U.S. Atlantic continental shelf. Her work resulted in key insights on subduction anisotropy and mantle flow near, for example, Japan, Tonga, Alaska, Oregon, Peru, and the Caribbean and Scotia Arcs.
Maureen’s early studies showed that anisotropic fabric in the mantle beneath subduction zones is pervasively trench parallel, which suggests a component of flow perpendicular to plate motion. This discovery implied that slabs do not merely sink vertically but roll backward, squeezing the mantle out of the way and parallel to the
trench. However, with new data, Maureen showed that while subduction zones attached to old plates have trench-parallel fabric, younger ones have trench-perpendicular fabric; this suggests that subducting plates transition from steadily subducting to foundering backward, depending on their age.
Maureen’s contributions extend beyond studying subduction zone flow. She and colleagues used their Peru data to show that shallow slabs are weak and undergo extensive internal deformation. Her analysis of anisotropy in the lower mantle indicates flow deflected by chemically stable “piles” (large low shear velocity provinces) at the core-mantle boundary. Her recent work on anisotropy in the mantle transition zone and the lithosphere beneath continents has yielded new insights into deformation in these regions of the mantle.
Maureen Long is a rising star of mantle seismology and dynamics. With her field programs and interdisciplinary approach, she has made, and will continue to make, lasting discoveries about subduction zones and how the Earth’s mantle convection engine works.
Thank you to AGU for this tremendous honor and to Dave Bercovici for the generous citation, for spearheading my nomination, and for years of mentorship and support. I am delighted to be named as a recipient of the Macelwane Medal, not least because I am grateful for the rare privilege of being able to thank my mentors, students, and collaborators in a public forum.
I decided that I wanted to become a geophysicist in middle school, after learning about plate tectonics in science class and realizing that it was the coolest thing I had ever heard of. Not many people see their career dreams at the age of 12 realized, and the fact that I have is due to my good fortune in having a string of extraordinary teachers and mentors. My professors at Rensselaer Polytechnic Institute treated me like a scientist from the day I walked in the door as a freshman, and two summers as a summer intern in Shun Karato’s lab introduced me to seismic anisotropy—I’ve been hooked ever since. I pursued my Ph.D. in the fantastically rich environment of the Department of Earth, Atmospheric and Planetary Sciences at Massachusetts Institute of Technology; Rob van der Hilst was a consummate thesis advisor, and I’m grateful for his mentorship. My time in postdoc paradise at Carnegie was a joy, and working with David James and the late Paul Silver—whom I miss dearly—was a privilege. Since moving to Yale, I’ve been fortunate to be part of an outstanding department and an exceptional cohort of fellow junior faculty.
I share this recognition with a large group of collaborators with whom I’ve worked and adventured—thanks to all of you for your brilliance, your friendship, and for making my science better. It has been an honor to work with my extraordinary students and postdocs, especially Juan Aragon, Neala Creasy, Caroline Eakin, Heather Ford, Xiaobo He, Colton Lynner, Karen Paczkowski, and Erin Wirth. As a seismologist, I feel fortunate to be part of a scientific community that encourages early-career scientists, fosters collaboration and cooperation, and increasingly values diversity.
Most important, I am grateful to my parents, siblings, and family for their love and support over the years. Above all, a huge thank you to my husband, Tony, and our children, Patrick and Caroline; you are the light of my life and I would never be able to do the work I do without you.