Tuncel Yegulalp | Going to Extremes

Tuncel Yegulalp
Professor of of Earth and Environmental Engineering
This profile is included in the publication Excellentia, which features current research of Columbia Engineering faculty members.
                               Photo by Eileen Barroso

“Extreme” is perhaps the last thing that comes to mind when talking to Tuncel Yegulalp. “Orderly” and “soft-spoken” seem more appropriate. Nevertheless Yegulalp was the last student of Columbia Professor E.J. Gumbel, who helped found the field of extreme value statistics.

Today, Yegulalp is a leading expert in the field, which is used to analyze and predict statistical outliers of common events, such as large earthquakes and severe floods, as well as the failure strength of rocks. In addition, his career has recently come full circle, returning him to the fields of mining and geology, only this time he’s trying to figure out how to put something into the ground—namely, carbon dioxide—rather than remove it. Yegulalp arrived at Columbia in 1963 to continue his studies of uranium mining.

It was during that time he discovered “there was more to the world than just uranium,” he said. That world included a graduate course in extreme value statistics—a class for which students had to be interviewed and handpicked by Gumbel. Yegulalp tried to use extreme value analysis to develop a statistical model of large earthquakes, but gaps in the seismic record made it impossible to create accurate forecasts.

Yegulalp eventually devised a new method to allow for the data gaps, but it wasn’t until 1999 that he was able to verify his work. While on vacation in Turkey, he experienced the magnitude 7.6 Izmit earthquake. The quake fit squarely into the range of what might be expected, given its magnitude and the time since the region’s last large event.

These days, Yegulalp is teaching extreme value methods to an entirely new group of students who are interested in understanding and predicting extremes of climate that might arise in the wake of global warming. At the same time, he is applying his expertise in geology and mining to projects focusing on geologic sequestration of carbon dioxide. The idea is that pumping carbon dioxide into minerals that contain magnesium will form magnesium carbonate, a stable solid that will keep the greenhouse gas out of the atmosphere permanently.

The only problem, he said, is the sheer volume of the carbon dioxide we will eventually have to sequester and the large amount of magnesium carbonate rock that it will result.

“If we want to maintain coal as a major contributor of energy, we will have to mine at least six billion tons of rock per year and learn to dispose of an even greater weight and volume of magnesium carbonate,” said Yegulalp. Spoken like someone with a mind for extremes.

M.S., Istanbul Technical University (Turkey), 1961; Eng.Sc.D., Columbia, 196

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