Miaki Ishii

2009 James B. Macelwane Medal Winner

Harvard University

Peter J. Huybers, Miaki Ishii, and Benjamin P. Weiss were awarded the 2009 James B. Macelwane Medal at the AGU Fall Meeting Honors Ceremony, held on 16 December 2009 in San Francisco, Calif. The medal is for “significant contributions to the geophysical sciences by a young scientist of outstanding ability.”


I have known Miaki Ishii for a long time—half her life—beginning with her undergraduate degree in physics at the University of Toronto. The academic world is marked by a certain transience—you meet incredible young adults of great promise, spend time teaching and mentoring them, and then they disappear into the world. I count myself extremely lucky that one such student—a young woman of singular talent and originality—decided to stay in the academic world of Earth science. So I now have the opportunity to watch her grow, see her make astonishing scientific discoveries, and, on occasion, participate in honoring her achievements, in this case, Miaki’s exceptionally well deserved Macelwane Medal.

Miaki is responsible for at least three transformative results in seismology and geophysics, each of which would have been sufficient to have her considered for the Macelwane Medal. These accomplishments reflect a rare talent for the theoretical and technical aspects of her field and an audacious scientific mind.

As a graduate student at Harvard, her supervisor Jeroen Tromp suggested several possible projects, and Miaki chose the riskiest. Specifically, she began working to estimate lateral density variations in the Earth’s mantle using seismic normal mode data. In a highly cited paper, she concluded that the lowermost mantle is characterized by denser than average material beneath the Pacific Ocean and Africa, thereby providing strong evidence for compositional heterogeneity in that region. Her work continues to be the framework for an energetic discussion at the interface between seismology, geodynamics, and geochemistry. And her perseverance showed that a quiet demeanor belies a very determined spirit.

Miaki next turned her attention to seismic anisotropy of the inner core. She combined normal modes and body waves to isolate a region at the center of the Earth that shows an anisotropy orientation that is distinct from the overlying inner core. The work, with Adam Dziewoński, is in some sense the discovery of a new region of the Earth—the “innermost inner core”—and it provides a fundamental boundary condition on inner core formation and dynamics.

As a postdoc at Scripps Institution of Oceanography, Miaki broadened her experiences, and behind her continued scientific output lies the toil of a committed seismologist. She worked tirelessly to collect Hi-Net data from Japan, leading to a seminal study with Peter Shearer, Heidi Houston, and John Vidale in which the data were back-projected to map the 1200-km-long rupture associated with the Sumatran event of Boxing Day 2004. Miaki’s remarkable analysis showed that this giant event, which led to the tragic tsunami, lasted 480 seconds and was characterized by a steady rupture velocity of 2.5 kilometers per second.

Miaki has worked on many other topics, but my point about breadth is made. Her accomplishments reveal the vision of a brilliant scientist working at the forefront of her discipline. What they perhaps do not reveal is a personality that is humble and self-effacing, a sense of humor that is playful, and a basic human decency that sometimes blunts even my attempts to poke fun at her.

Small things deflect our trajectory in life, and it is possible Miaki could have jumped, as a graduate student, into the world of quantum optics. We would have heard about her nonetheless. All the same, it’s nice that I haven’t had to lament the disappearance of that one fine young undergraduate student—instead, I can, from a very short distance, celebrate her James B. Macelwane Medal from AGU.

—JERRY X. MITROVICA, Harvard University, Cambridge, Mass.


I am honored to be a recipient of the AGU Macelwane Medal. A fortunate life is one that is guided by patient, caring, and supportive mentors, and by that measure I have had a very fortunate life. It would be impossible to mention all of those who have influenced my life, but I would like to thank at least some of them.

First, I would like to thank Jeroen Tromp for converting a naive and stubborn graduate student into a researcher. Jeroen’s remarkable patience and unwavering support continue to help me move forward whenever I encounter problems.

As a graduate student, I had the good fortune to work with two other great seismologists at Harvard, Adam Dziewoński and Göran Ekström. Sybil and Adam Dziewoński have become dear friends, and in addition to rigorous seismology training, they made sure that I received a well-rounded education in American culture, ranging from the proper Thanksgiving dinner to an introduction to western movies with cowboys. My life at Harvard was, and is, further enriched by Renata Dmowska and Jim Rice. Their friendship and support remain somewhat of a mystery to me—I was not their student, nor did I work with them, yet they pampered and continue to pamper me as if I were one of their students.

Working with John Vidale and Peter Shearer has been a wonderful pleasure, and they helped to broaden my scientific experiences and outlook. Both John and Peter continue to inspire and stimulate my work and enrich my life.

My days at Scripps were further highlighted by tremendous generosity and input from Guy Masters, Gabi Laske, and Freeman Gilbert, all wonderful role models.

I am currently working closely with Eric Kiser and Irena Lucifredi, and the experience of being able to teach and be taught by them has been truly rewarding.

I would like to thank Jerry Mitrovica for being such an exemplary mentor for the past 16 years. Jerry has seen me through difficult times, and he has always been remarkably supportive. Also, I would not be a seismologist today if Jerry’s lectures in introductory physics had not convinced me to pursue a career in geophysics over chemistry.

Finally, I would like to acknowledge the patience and support my mother has given me for over 33 years. It must have been difficult to raise a child who got into so much trouble that there would be a call from school nearly every day. I will probably cause more trouble in the future, but I am sure she will continue to stand by me.

The AGU Fall Meeting is always overwhelming with so much information transferred in such a short time, and it is humbling to be reminded of how many important questions remain to be solved in the Earth sciences. Seismology, in particular, will always be an exciting area of research, and I will always be proud to be a part of our community of scholars and friends.

Thank you.

—MIAKI ISHII, Department of Earth and Planetary Sciences, Harvard University, Cambridge, Mass.