The potential-field geophysics community has lost a premier scientist and an exceptional human being. Richard Hansen passed away on 6 January 2008 after a long bout with cancer. He is best known for his influential research in potential-field interpretation techniques, his frontier work on airborne acquisition methods, and his selfless consideration of others. For much of his career, he held key or leadership roles in research and development at several small geophysical companies. He also spent considerable time in academia, notably as a professor and director of a research group at Colorado School of Mines. He served four terms as associate editor for GEOPHYSICS, and made significant contributions to the SEG Gravity and Magnetics Committee’s potential-field data exchange standards.
Hansen was born in Ottawa, Canada, and received an undergraduate degree in mathematics and physics from Carleton University in 1968. After graduation, he married Kathleen Thoms, and they headed to the University of Chicago where he obtained a PhD in physics with a thesis in general relativity titled, “Multipole moments of stationary spacetimes” that is still referenced to this day. With his newly acquired PhD, he began two happy and productive years at the University of Pittsburg, where his interest in Roger Penrose’s theory of twisters led Hansen to a postdoctoral position with Penrose at Oxford during 1975–1976.
In later years, he took advantage of his training and experience in general relativity. Many of his geophysical algorithms use tensor constructions not commonly seen in potential-field geophysics. Such constructions allow both simplification of the derivations and presentation of the final results in a very elegant manner. This elegance is present in all his publications, making them a pleasure to read.
From 1976 to 1978 he was a lecturer in mathematics at the University of California, Berkeley, where he did research and taught various courses. In 1978, he was hired by Geometrics as staff scientist. From there he had an apprenticeship into the realities of providing mathematical support for an aeromagnetic contracting operation. In 1985, after the Airborne Division of Geometrics succumbed to economic conditions, he was hired first as senior scientist, and later as research professor, and finally director at the Center for Potential Field Studies, Colorado School of Mines (CSM). At CSM, he worked with graduate students in developing algorithms to meet expressed geologic needs for the oil industry. During his tenure at CSM, he supervised eight master’s theses and seven doctoral dissertations. When mergers and economic conditions led to dwindling support for the Center in 1995, he joined Pearson, deRidder, and Johnson (PRJ) as principal geophysicist. He worked closely with Ed deRidder and became president of PRJ in 2003 after deRidder’s death. After PRJ merged with EDCON, Hansen became the senior vice president of the new company EDCON-PRJ, a position he held until his death.
He coauthored with Frank Hadsell the second volume of the SEG publication Tensors in Geophysics, with Alex Kaufman the Principles of the Gravity Method, published by Elsevier, and was senior author of the chapter on magnetic methods for the SEG book Near-Surface Geophysics. He published more than 30 papers in refereed journals in which he pioneered novel and innovative interpretation techniques now widely used by industry. He demonstrated the advantage of using multisource depth determination techniques for potential field data by developing the required theory and the strategies needed for implementation. He was one of the pioneers in using spectral analysis for Curie depth estimation and of spectral shifting for 3D magnetic interpretation.
He also made significant contributions to the existing techniques for drape-flying corrections, reduction to the pole, extended Euler decomposition, and analytic signal—all of which are now incorporated in existing interpretation tools. For his many contributions to potential fields he was elected an Honorary Member of SEG in 2003.
Hansen was an accomplished musician. He learned to play the cello in high school, and in graduate school he was a member of a string quartet. Later, he played with the San Francisco Community Orchestra and the Jefferson Symphony in Colorado. He remained active in chamber music up until a month before his death. In 1996, he played at the Icebreaker at SEG’s Annual Meeting in Denver as part of a violin/flute/cello trio. Hansen also enjoyed folk music and loved to play with his guitar or banjo. The sense of being productive in music as well as at work was very important to him. His other interest in life revolved around cats, a passion he shared with his wife, which resulted in an Internet store devoted to cat products.
Hansen will be remembered by his colleagues for his seminal contributions to potential fields, for his contagious enthusiasm, childlike curiosity, overwhelming optimism, and for his unselfish help to others. He is survived by his wife Kathleen of Arvada and his sister Leonora of Ottawa. Hansen’s death is a tremendous loss to the potential field community