Lush plants compete for space with books and papers in the sunroom at the rear of Pradeep Talwani’s suburban home. The geophysics professor retired more than 15 years ago, but he hardly gave up scholarly pursuit.
Since retiring, Talwani has edited a book about intraplate earthquakes and co-written, with a former student, the history of earthquakes in South Carolina, where the East Coast’s largest intraplate earthquake in recorded history occurred in 1886.
Seismic activity was Talwani’s bread and butter during a 36-year career at USC, and the research interest continued beyond retirement, but his latest project is broader in scope.
“A Journey of Ideas about the Earth,” the working title of his 400-page manuscript scattered across the sunroom table, is a reckoning of the history of scientific ideas across many cultures, beginning 5,000 years ago. Oxford University Press green-lighted the project last year.
“As civilizations, we learn through a journey of ideas,” Talwani explains. “Everything starts somewhere, and the ideas develop whenever you have what I call ‘bright ages’ in which, say, a benevolent king or caliph would foster think tanks — kind of like a well-funded research university today — to develop ideas.”
He recounts the tale for one such idea, the invention of the mathematical symbol zero, which we take for granted now. Talwani has traced the representation of zero to an obscure cache of birch bark sheets in present-day Pakistan that date more than 1,000 years before the first mention of the neutral number in Europe.
During his career at USC, Pradeep Talwani could often be found out in the field hunting for clues about the Earth’s geological past. Here, Talwani looks for evidence of prehistoric earthquakes at Fort Dorchester in Summerville, South Carolina.
“How an idea evolves had been in the back of my head since I was an undergraduate at Delhi University,” he recalls. “Honors students had a one-year series of lectures on the history of science, and we enjoyed those stories so much. When I started teaching, I always tried to find the origin of an idea — where it came from, not just who perfected it or got the credit.”
Talwani’s own career could likewise be described as a journey of ideas. It began more than 60 years ago when his older brother, then a geophysicist at Columbia University, sent postcards to him from research excursions in Argentina, West Africa and the Mediterranean. “He was on a research ship for weeks at a time,” says the younger Talwani. “I remember thinking, ‘What a nice gig. Geophysics seems like a great field!’”
Talwani subsequently earned a master’s in geophysics from the Indian School of Mines, then accepted an oil exploration job with India’s Oil and Natural Gas Commission. “It meant living in tents and moving every few weeks,” he says. “It was a great life, but then I got married, and I had always wanted to get a Ph.D.”
A scholarship from Stanford University brought him to the U.S., where during five years of doctoral study he and his advisor conducted research with NASA’s Apollo lunar missions. “NASA had data from so many different experiments, and each data set provided a set of constraints that eventually helped you see the big picture,” he says. “That became my style of doing science: To understand something, I would look at every possible data set related to the topic.”
“As civilizations, we learn through a journey of ideas. Everything starts somewhere, and the ideas develop whenever you have what I call ‘bright ages’ in which, say, a benevolent king or caliph would foster think tanks — kind of like a well-funded research university today — to develop ideas.”
When he joined USC’s geological sciences faculty in 1973, he began absorbing everything he could about the 19th-century Charleston earthquake, which killed more than 100 people and was felt as far away as St. Louis and New York City. That led to him working with the U.S. Geological Survey, which was installing seismic networks around the state in parallel with a surge in nuclear power plant construction.
“Memory of the Charleston earthquake had been a concern when the V.C. Summer Nuclear Station was being built in Fairfield County in the 1970s,” Talwani recalls. “So I got in on the ground floor of installing seismic detectors around that plant before construction was completed.”
He conducted research on reservoir-induced seismicity, a tremor-producing phenomenon that occurs after large lakes are created, and was also director of the South Carolina Seismic Network.
“In the nearly 40 years I was at USC,” he says, “I gained expertise in reservoir-induced seismicity because of our studies on the 5,000 tremors we located over time across South Carolina and related work I did in Egypt, India, China, Vietnam, Germany and Canada.”
A seminal paper Talwani wrote on the mechanism of water-induced seismicity has been cited more than 500 times worldwide.
He also became a consummate teacher. In 2001, his research approach became the basis for a new South Carolina Honors College course that explored the evolution of ideas about the shape, size and age of the Earth. The course was fun to teach, he says, and it further fueled interest in his current book project — a more comprehensive history of science that includes contributions not always credited in Western textbooks.
“The traditional history of science starts with the ancient Greeks, then mentions the Dark Ages in Europe and the scientific revolution. But something else must have been happening with scientific ideas during the Dark Ages,” he says with a wry grin, reclining in his sunroom. “I mean, the rest of the world was OK, right?”