Phone: (845) 365-8389
Fax: (845) 365-8150
I currently work part-time at Columbia University, as a “Special Research Scientist” and Principal Investigator, on projects funded by various US government agencies.
I had a full-time teaching career at Columbia from 1971 to 2008, studying elastic wave propagation, earthquake physics, and Earth structure. I was fortunate in 1975 to be asked by Kei Aki to write a textbook with him, on Quantitative Seismology. It has been translated into Russian, Chinese, and Japanese. As of 2015 it is still print, and has enabled many contacts around the world. My most exciting research was in 1996, when Xiaodong Song and I discovered seismological evidence that the solid inner core of the Earth, in recent decades, has been rotating eastwards a few tenths of a degree per year with respect to the mantle and crust. The inner core is about the size of the Moon, and sixty times nearer to us. For it to be moving at a rate perceptible on human time scales, is a remarkable feature of our planet. I described basic ideas on this work in a Jeffreys lecture, given to the Royal Astronomical Society.
After chairing the Department of Geological Sciences at Columbia (1979 to 1983) I took a service leave from academia to work in Washington for twelve months, in the unit that wrote President Reagan’s Report to the Congress on Soviet Noncompliance with Arms Control Agreements. It was fascinating at that time to interact with worlds of which I had known very little---the military, the monitoring agencies, the labs that design and engineer nuclear weapons, the policy agencies, and people on Capitol Hill. I was asked to evaluate claims that the U.S.S.R. had carried out underground nuclear explosions with yields larger that the 150 kiloton limit associated with the bilateral Threshold Test Ban Treaty. (I have a book chapter on part of this experience, published about thirty years later.)
In the mid-1990s in the Clinton administration I went back to Washington for another year's service leave from Columbia, and was a small part of the large team that negotiated the Comprehensive Nuclear-Test-Ban Treaty---an experience that for me including presenting formally, in Geneva, for the United States, a way to manage problems associated with the conduct of large chemical explosions. Since returning to Columbia I have maintained links with the U.S. Air Force (which leads U.S. efforts in monitoring for compliance with test-ban treaties), with the U.S. Arms Control and Disarmament Agency, and later with the Bureau of Arms Control in the Department of State (after the Clinton administration abolished U.S.A.C.D.A. in the late 1990s at the behest of Senator Jesse Helms). I have also worked with the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), which was set up in 1996 with its headquarters in Vienna, Austria. It is an interim organization tasked with building up the verification regime of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in preparation for the Treaty's entry into force, as well as promoting the Treaty's universality.
I started out in research with a mathematics background, and an interest primarily in the theory of seismic wave propagation, and then in methods to understand how the recorded shapes of seismic waves are affected by processes of diffraction, attenuation, and scattering. But over the years my work has become more and more practical, and much more data-based. Since the 1990s I have focused on the development of seismological methods to improve monitoring of both earthquakes and explosions. It is remarkable that for more than a hundred years the main procedures for locating earthquakes and explosions, as used by agencies that publish the location of hundreds of seismic events each day, have seen very little change---even though methods have become available to make location estimates, and estimates of event size, with precision that is greatly improved over that achieved via the traditional methods.
In 1987 Columbia University appointed me as Mellon Professor of the Natural Sciences, a title established/funded by the Mellon Foundation to recognize an academic at Columbia who in middle age had made a switch in careers. In practice I carried on with geophysics research, but maintained connections with agencies involved in monitoring compliance with nuclear arms control treaties---most specifically, with nuclear test ban treaties. In 2003 I initiated an undergraduate science course at Columbia titled “Weapons of Mass Destruction” that reviewed how these weapons work, what happens to their environment when they are used, how they are made and who has them, and the efforts that have been attempted to bring them under control. My work has continued in geophysical research but more and more I became involved with institutions outside academia, so in 2008 I gave up my professorship. I appreciate being able to continue with research and to keep an office at Lamont---but am now more free to travel. I continued teaching the WMD course through 2013, and still give guest lectures though the course is now the responsibility of the Department of Physics.
Outside my office and home, I am an organist, sing in various choirs including that of Grace Episcopal Church, Nyack, NY, and still sail small boats---but have given up wind-surfing for tamer pursuits.
That's it on this page, for paragraphs about “I” and “me” and “my.” To conclude with a list of links: