Xavier Le Pichon, a French geophysicist who revolutionized the way in which a pioneering model of the Earth’s tectonic plates was able to understand the movement of the Earth’s crust, and died on March 22 at his sister’s home in southern France. He was 87 years old.

His death was announced in a statement from Collegie de France, France’s premier educational institution. There, Dr. Le Picon was Professor Emeritus and Chairman of Geodynamics.

Dr. Le Picheon, who internized in Japanese concentration camps as a child, continued to build a second career as a deep sea explorer, working with Mother Teresa of India for a while. However, it was in the field of geodynamics that he made his biggest contribution. Use a computer to create a model of the Earth plate.

His formulation has six such plates, as he said when he won in 2002, “for what is essential to the structural symptoms of the Earth’s surface.” Balzan PrizeAwarded in science fields not covered by Nobel.

Plate tectonics with Earth’s surface studies is a “framework” for understanding earthquakes, volcanoes, and the Earth’s long-term “climate stability.” David BelkovichYale geophysicist. He added that Dr. Le Picon was one of the architects of the framework.

Professor Bercovici emailed him “one of the giants of the plate structure revolution, especially when practicing its mathematical theory.”

His work was built on the theory of plate tectonics developed by Princeton scientist W. Jason Morgan in 1967. “Now we are entering an age of quantification for tectonics,” wrote Dr. Le Picon.

“The University of Rochester has a great opportunity to develop a new world of geophysics,” said John Taldono, professor of geophysics at the University of Rochester.

Dr. Pichon came to view the Earth as “an extraordinary creature with ocean and continental movement.”

After years of studying the ocean and its floors, including Columbia University, Dr. Lupicheon achieved a breakthrough in the mid-1960s. He called the “incredibly unpleasant” months of cruise hosted by Columbia, and observed a 37,000-mile-long ridge in the South Atlantic and Southwest Indian oceans.

The object was to detect seismic activity along the coat of arms of the ridge and test predictions made in the 1950s by Jean Pierre Rothet, another French scientist. “We went zigzag on this famous earthquake line for nine months,” Dr. Le Picon wrote in his 2003 book, Plate Tectonics: The Insider’s History of Modern Theory of the Earth.

The trip confirmed it and he continued to earn his Ph.D. Based on that study, at the University of Strasbourg in 1966.

“As such, the central ridge has achieved a victory over tectonics, becoming the most important structure in the world due to stroke,” he wrote.

But this was in the early 1960s, and he ran “in what we call “fixed mentors,” things weren’t moving.” Like he put it down On the 2009 episode of the podcast “Being With Krista Tippett.”

“The Earth was considered everything to be a static place,” he said. “Things were moving up and down, but never sideways. The continent was always there. The ocean was always there.”

Dr. Le Picon initially defended these concepts, but he realized they were wrong. He returned from the lab one day and told his wife, “My paper’s conclusions are wrong.”

Rather, I felt that he was an American geologist. Harry Hess The assumption in 1962 that the seabed had continued expansion was correct. After all, there was seismic activity along the top of the ridge. Measuring magnetic anomalies along the ridge is important in proofing Dr. Hess’s hypothesis.

Dr. Le Pichon recalled his Eureka moment in an episode of the podcast. “I worked all night on a computer, and one night I put it all together and found out that Hawaii approaches Tokyo at 8 centimeters each year.”

He recalls what he told her: “I discovered how the Earth works. I really know that now.” And I was so excited. ”

His passion for what was happening under the ocean developed quickly. After growing up in what was a French protectorate in Vietnam at the time, he was interrupted by his family during World War II when Japan invaded.

“When I was in the concentration camp, we were on the Pacific coast, and I was wondering what was under the water, and I was on the beach,” Dr. Le Picon said in 2009.

After publishing his groundbreaking paper in 1968, Columbia and Massachusetts Institute of Technology presented the first quantitative global model of plate boundaries and movement, offering him a teaching position. However, he instead led the Institute of Oceanography in Brittany, France, where he began his second career as an underwater ocean explorer, advancing into the depths of small submarines on joint Franco-American expeditions.

In 1973, he said he had taken such a ship 3,000 meters below him while exploring the ridges in the Mid-Atlantic Ocean.

“I had the impression that I was a religious man and had the return to Genesis,” he added. Other sea floor trips in Greece and Japan followed.

Dr. Lupichon, a Roman Catholic who attended Mass every day since childhood, experienced what was called a “great crisis in my life” in 1973 and worked for Mother Teresa in the city of Calcutta, India.

“I was very immersed in my research. I wasn’t looking at anyone else anymore,” he said. “In particular, I didn’t see people suffering and difficulties. It was a very strong crisis.”

His experience in Calcutta changed him by his account, and then he, his wife and his children engaged in charity and charity in the French Lach community for people with intellectual disabilities. They lived there for nearly 30 years. He and his family then find a similar community and help them live there.

Xavier Thaddée Le Pichon was born on June 18, 1937 in Quy Nhon, Vietnam, France, to Jean Louis Le Pichon and Helene Pauline (Tyl) Le Pichon, rubber plantation managers.

The family moved to France in 1945, with Xavier attending the Institute of Cherbourg Saint Paul and the Lyce Sainte Geneviève in Versailles. In 1960 he received his Bachelor of Engineering from the Institut de Physique Du Globe He received a Fulbright Fellowship in Strasbourg to study at Columbia University’s Lamont Daughertier Observatory.

His original works will be carried out over the next decade, and in 1973 he wrote with Jean Bonnin and Jean Franciteau.

In the 1970s and 1980s, Dr. Le Picheon taught at the Sorbonne and Ecole Normal Superfoil. He became a professor at the French Collège de France in 1986 and remained there until his retirement in 2008. Besides Balzan, he won many awards and was a member of the National Academy of Sciences in the United States.

He was survived by his wife Bridget Suzanne (Barselmee) le Pichon, a pianist. His children, Jean Baptist, Marie, Emmanuel, Raffaère, Jean Marie and Pierre Guien. 14 grandchildren; 5 great grandchildren.

In lectures and interviews, Dr. Le Picon linked his discoveries to his Catholic faith as a scientist and the prayer work it stimulated. The bridge between them was his concept of “vulnerability,” and he said, “is the essence of men and women, at the heart of humanity.”

The earth is also vulnerable. “I have a very close relationship with the Earth, so I think a little like a mother,” he said in 2009.

Sheila McNeill and Daphne Angles Contributed research.