Anthony Brian Watts receives the 2020 Maurice Ewing Medal


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Anthony Brian Watts

Anthony “Tony” Watts, a distinguished marine geophysicist, has made a number of fundamental contributions to the study of the structure and evolution of the world’s ocean basins and their margins. His pioneering work on isostasis and bending of the oceanic lithosphere led to the explanation of the origin of island arcs, deep-water trenches and mountain belts, the deep structure of continental margins, oceanic islands and mountains below. -marines, and the relative role of oceanic plate processes in relation to mantle dynamics in contributing to Earth’s gravity and topographic fields. His lifelong work is very elegantly presented in the book Isostasis and bending of the lithosphere. By comparing the predictions of simple elastic and viscoelastic plate models to gravity, geoid, and bathymetry data in the vicinity of oceanic islands and seamounts, he was able to constrain elastic thickness, an approximation of long-term force. term of the oceanic lithosphere, and showed that the elastic thickness depends on the age of the oceanic lithosphere at the time of loading. He extended this method to the loading of sediments on the continental margin, making it possible to understand the evolution of sedimentary basins.

In order to further confirm the bending effect due to large geological loads directly, rather than inferring them from gravity and geoid data, Tony has conducted a number of large-scale seismic reflection and refraction experiments in the Atlantic and Oceanic Oceans. Peaceful. His seismic experience in the Hawaiian Islands showed that the island load caused the Pacific oceanic crust to flex downward immediately under the load and upward in the flanking regions. Seismic data has revealed the very first evidence of a magmatic underlay under an ocean island. He then conducted seismic experiments over the Canaries, Cape Verde Islands and the Louisville Ridge which revealed evidence of other phenomena such as relaxation of viscoelastic stresses in bending moats, dynamic mantle tilt. and the lifting of the moat in flexion.

Tony doesn’t like the word “retire” and has remained very active in acquiring new data and working with students and post-docs. In addition to doing research, Tony has been at the forefront of training the younger generation of marine geoscientists and has trained over 50 doctoral students. students and post-docs, who have become leaders in their field. He has been an inspiration to many of us and has played a key role in the global marine geophysics community. I want to thank Tony for his leadership over the past 40 years and invite you to join me in congratulating him on the 2020 AGU Maurice Ewing Medal, a well-deserved honor.

—Satish Singh, Paris Globe Physics Institute, France

Reply

Thank you, Satish, the US Navy and AGU for this Maurice Ewing Medal award. It is a great honor for me because I have long admired “Doc” Ewing, his vision and his passion for exploring the oceans. I remember well when, as a young scientist, I first met him a few days after my arrival in Lamont.

There are a lot of people I would like to thank for this award. The late Martin Bott, my doctorate. thesis supervisor, and Bosco Loncarevic and Manik Talwani, who first gave me the opportunity to go to sea and explore the world’s ocean basins and their margins.

Lamont in the early 1970s was a hive of activity that ran three research vessels to the four corners of the world’s oceans. Shortly after my arrival, I found myself on the Vema, combating the Atlantic swell and Lamont’s unique two-wire operation “core and camera per day” between the collection of new geophysical data. The late Walter Pitman and Manik were using magnetic data to reconstruct the opening of the Atlantic, and I was keen to use gravity data to learn more about the stiffness of the plates and test the hypotheses that made such reconstructions possible.

Unraveling the history of flexure, its history and its universality has been a fascinating learning experience, and I would like to add a special thank you to Dick Walcott for his early encouragement; Jim Cochran for his work on sediment and volcanic loading; Paul Stoffa, Peter Buhl, Christine Peirce, Donna Shillington and Robert Dunn for their help in facilitating complex seismic experiments at sea to test the bending model; the late Evgenii Burov and Shijie Zhong for their knowledge of the relationship between bending and rheology of the crust and mantle; and last but not least, my extraordinarily talented students, too numerous to name here, who have continued and taken the subject to even higher levels.

We live in an age when the ocean continues to play a vital role in the science of the earth system. But only about 15% of the seabed has been mapped in detail, and imagery of underwater structures is limited. So I’m excited about the Seabed 2030 project to map the entire seabed, the International Ocean Discovery Program project to drill down to oceanic Moho and sample the pristine mantle, the ultradeep seismic projects that are planned to image the entire ocean lithosphere / asthenosphere system, and the challenges it will pose to the next generation of marine geoscientists.

—Anthony Brian Watts, University of Oxford, Oxford, UK


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