Every year the Geophysical Society of Houston (GSH) holds its Spring Symposium, and for the past decade or so an honoree has been chosen based on his or her contributions to the industry.

When the GSH announced that Leon Thomsen was this year’s honoree, many of the members muttered, “It’s about time!”

Thomsen is arguably one of the most famous geophysicists in the world and has probably been published more than I have even though I’ve been a full-time writer for 25 years. His topics have been wide-ranging, but he’s most noted for a single concept—anisotropy.

Anisotropy is defined as an inequality in physical properties along different axes. It seems obvious enough that anisotropy should not be ignored when interpreting seismic data, yet it was such a complex mathematical challenge that it was, indeed, ignored for many years. Thomsen set the world straight in 1986 with a paper narrowing down the parameters needed for anisotropic studies. It is, to this day, the most frequently cited paper in Geophysics.

During a roast in Thomsen’s honor at the symposium, his former Amoco colleague Gerry Beaudoin joked that Thomsen’s ground-breaking work was not welcomed at first. “In the beginning, there was Earth,” Beaudoin said. “The earth was simple, uncomplicated and isotropic. And we were happy! Into this paradise that we only dimly remember today, Leon strolled and began raising hell.

“Our world changed forever. We should have seen this coming.”

Thomsen is slightly more modest about his impact. In a 2011 interview he told me that, while he’s been trying to get his wife to call him “Dr. Anisotropy” for years, his concept wasn’t actually that complex. “The ideas that I’m famous for are really quite simple ideas that I came across in a period of a few weeks 30 years ago,” he said. “Yet they’ve been extraordinarily useful to so many people.”

Thomsen, who teaches at the University of Houston in addition to running Delta Geophysics, encourages his young charges to be guided by their intuition. “You can stand in front of any rock outcrop and realize that the rock must be anisotropic,” he said. “But it was ignored for so many years. I can’t think of how many field trips I’ve been on where the leader is talking about the sedimentology and sometimes the tectonics but rarely if ever about the structural features in the rock that lead to anisotropy. Here’s this first-order effect that’s obvious to anyone standing in front of almost any rock mass, and yet we’ve excluded it from our analysis. That can’t be a smart thing to do.”

During Beaudoin’s roast, he showed the titles of a couple of papers that Thomsen had written prior to his seminal 1986 publication. One dealt with the Earth’s atmosphere, while another discussed equations of state on the terrestrial planets. “Here I was making maps, focused on mundane, worldly stuff, and you could say my world was tidy, orderly and small,” he said. “I say these papers are evidence that Leon will never be accused of thinking small. I think for these reasons we should have understood that something was going to happen when he walked into our garden.

“This apostle of anisotropy has really converted a lot of us. And I want to say to the apostle, thank you for changing the way we see and describe this richly elastic Earth.”

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