Late one night in January, just 12 days after the earthquake that devastated Haiti, Eric Calais touched down at the shattered Port-au-Prince airport in the cockpit of a Boeing 727 weighed down with humanitarian aid and geology equipment. It was no consolation to the Purdue University geophysics professor that he had warned the nation's leaders two years earlier to ramp up their earthquake preparedness, after he projected that a 20-mile-long fault line under Haiti had the potential to cause a 7.2-magnitude quake.

Mr. Calais, 46, returned to Haiti for two reasons. He was leading a National Science Foundation mission to study the earthquake's epicenter while it was still fresh. And he wanted to check up on the friends he had made during two decades of visiting the island nation. Some of them, he would learn, had perished beneath the rubble.

"When a large earthquake occurs, geoscientists are always very interested in going to the earthquake site as quickly as possible because it's an opportunity to learn," Mr. Calais says. "But the priority after the earthquake was not doing science; it was humanitarian support."

In April he went back to Haiti to apply his geophysics expertise in a new role: developing public-safety policy as the co-chair of the United Nations Development Programme's Disaster Risk Reduction Task Force there. During his one-year term, Mr. Calais will work with Haitian scientists, government officials, and aid workers to build a permanent national agency for seismic-risk reduction that will teach government officials how to prepare for earthquakes. He will also advise international investors and organizations like the World Bank on seismic risk.

Mr. Calais traded his Purdue laboratory—where he has been since 2001—for a dusty steel freight container just outside the Port-au-Prince airport. He has braved the tropical heat and rain, and now has to be constantly vigilant against cholera.

Dealing with government bureaucracy and politics has meant a steep learning curve for scientists like Mr. Calais. Government and U.N. officials "think about these problems in different terms," he says. "I really had to twist my brain in a completely different way in order to operate."

He felt similarly in 2008, after nearly two decades of studying Northern Caribbean geology—starting with his dissertation at the University of Nice, in France—convinced him that Haiti was vulnerable to a seismic event. In meeting after meeting with government ministers and international donors, Mr. Calais says, the response to his warnings was always the same: "This is a very interesting story that you're talking about, but there is nothing that we can do about it."

Haitian officials, plagued for decades by political turmoil, hurricanes, and poverty, just had more immediate concerns, Mr. Calais says.

But that attitude has changed. When efforts to rebuild the country began after the earthquake, the Haitian government was paying much more attention to what was happening beneath its feet. The United Nations and foreign-aid agencies shared its concern. And Mr. Calais's experience bridging the policy and science divide made him a natural choice to lead risk-reduction efforts, said Thomas Pitaud, technical specialist for the U.N. disaster-relief-management program. "We cannot develop the country without having a good knowledge of the risk."

Though planning has just begun, Mr. Calais has had an early victory in gaining the government's support for seismic microzoning—studying regional geology to identify plots of land most prone to destruction during a quake. The prime minister and public-works agencies are reviewing microzoning data collected immediately after the quake, which will direct reconstruction for the entire capital city of Port-au-Prince, and hope to survey other urban areas once the money is available.

Developing a national seismic-risk-reduction plan will require considerable investment in education. According to Mr. Calais, Haiti has a shortage of geologists and engineers trained to do the survey work, and many Haitian researchers have left government and academe for better-paying jobs in industry. "Even though there are potential scientists and researchers, they do other things on the side," he says. "They are very busy making money and trying to sustain their families."

That leaves the majority of research work to visiting scientists and graduate students from the United States and Europe, who take their expertise with them when they leave.

Mr. Calais has an even greater worry. The Haitian fault line released only about 10 percent of its stored energy when it shifted last January, and the remaining energy could set off an even larger quake at any time, he says. Although the plates beneath Haiti had been pretty stable for 50 years, he says, the country has a long history of seismic activity. "It gives us a false impression of safety," he says. When the earth is quiet, he says, "it's storing the energy it needs" for its next release.

Kudos to Dr. Calais for applying his expertise in a humanitarian fashion.