(1933- ) Indian Geophysicist
There are two parts to the measured gravitational field, the main field of the Earth and the anomalous field. The anomalous field reflects any body of rock in the crust that does not have a density of 2.65 gm/ml, the average density. Before Manik Talwani, the anomalous field was separated from the main field and geometrically evaluated to estimate the type of body that might be producing the anomaly. Talwani developed mathematical methods to model the shape and density of the subsurface body or structure that produced the anomaly. He first developed methods to model it in two dimensions but later methods modeled bodies in three dimensions, both using integral calculus. He later extended the same methods to magnetic data. These elegant methods sparked a revolution in field geophysics. Much old data were reevaluated with the new methods and astonishing new structures and bodies were revealed. The methods were quickly adopted by the petroleum industry greatly increasing their exploration success and allowing them to find new targets that previously were not even imagined. The methods were written as interactive computer programs that are in use today in both research labs and classrooms with virtually no alteration to the now more than 35-year-old equations. The papers introducing these breakthroughs are “Rapid Computation of Gravitational Attraction of Three-Dimensional Bodies of Arbitrary Shape” and “Computation with the Help of a Digital Computer of Magnetic Anomalies Caused by Bodies of Arbitrary Shape.”
Manik Talwani applied most of his geophysical ability to studies of the oceans. To accurately measure gravity on the research ships, he invented a cross-coupling computer to compensate for the roll of the waves. He went aboard submarines to make highly accurate pendulum measurements underwater. With these tools in hand, Talwani traveled the four corners of the world to do geophysical surveys over every type of plate tectonic margin in as many different variations as possible. He was even on a ship (R/V Vema) that took him to 81 degrees north latitude. Most of his efforts were to study the gravity of the various features but later in his career, he became interested in seismic reflection profiling of margins. Through the famous EDGE project, Talwani studied the U.S. East Coast, the conjugate South Atlantic margins off of Brazil, and Namibia, as well as the southwest margin off of India. A book resulting from this work is entitled Atlantic Rifts and Continental Margins. Much of his later research was tied to petroleum exploration during and after he was employed in the petroleum industry. In these studies, he uses both 3-D seismic reflection processing techniques and a new highly sensitive technique called gravity gradiometry.
Manik Talwani even designed and oversaw the “Traverse Gravimeter” experiment on the Moon. This project, which involved instrumentation design as well as surveying, resulted in the only gravity measurements ever to have been made on the Moon.
Manik Talwani was born on August 22, 1933, in India. He attended University of Delhi, India, and earned a bachelor of science degree in 1951 and a master of science degree in 1953. He earned his Ph.D. in geophysics at Lamont-Do-herty Earth Observatory of Columbia University, New York, in 1959. He accepted a research position at Lamont-Doherty in 1957 and a faculty position in 1970. He was the director of the La-mont-Doherty Geological Observatory from 1973 to 1981. He moved to Gulf Research and Development Company in 1981 as director of the Center for Crustal Studies and he became chief scientist in 1983. In 1985, he joined the faculty at Rice University, Houston, Texas, as the Schlumberger Professor of geophysics and the director of the Geotechnology Research Institute of the Houston Advanced Research Center. Talwani was a Sackler Distinguished Lecturer at the University of Tel Aviv, Israel, in 1988. Manik Talwani married Anni Fittler in 1958 and they have three children.
Manik Talwani has had an extremely productive career authoring some 150 articles in international journals and professional volumes. Many of his papers set benchmarks for geophysics that still stand today. He also edited five volumes. His research has been well recognized in the profession through numerous honors and awards. He is a member of the Norwegian Academy of Arts and Sciences, and a foreign member of the Russian Academy of Natural Sciences. He was awarded an honorary doctoral degree from the University of Oslo in Norway. He received the First Krishnan
Medal from the Indian Geophysical Union in 1965, the James B. Macelwane Award from the American Geophysical Union in 1967, and the NASA Exceptional Scientific Achievement Award in 1973. He was given the George P. Woollard Award by the Geological Society of America in 1983, the UNESCO Toklen Award by the National Institute of Oceanography of India in 1990, and the Alfred Wegener Medal by the European Union of Geosciences in 1993. Talwani was a Hays-Fulbright Fellow in 1973 and a Guggenheim Fellow in 1974.
Talwani has performed service to the profession that is too extensive to report here individually. He served as a member or an official of virtually every committee involving ocean studies, and geophysics for that matter, including the Joint Oceanographic Institute for Deep Ocean Sampling (JOIDES), the Joint Oceanographic Institute, and several committees in the National Research Council and the National Academy of Sciences. He also served on several committees for the American Geophysical Union and the Geological Society of America. He was even called upon to help resolve a boundary dispute between Iceland and Norway because he had intimate knowledge of the Norwegian Sea. In another case, he helped negotiate the first United States-China cooperative scientific project since World War II.
