Tanya Atwater: Using Plate Tectonics to Explain Geologic History of Western North America

Tanya Atwater dazzled North American geologists with her remarkable insight relating Pacific basin plate tectonics to geological history of western North America (Atwater, GSAB, 1970). As a seagoing graduate student making new discoveries about the plate kinematics of the northeastern Pacific, she wrote the seminal paper explaining many fundamental concepts all at once. Where and when was there subduction along the western margin of North America, and why did it end? Why did the San Andreas Fault form? How did the migration of triple junctions control the geological evolution of western North America? What happens when a ridge collides with a trench? She answered all these questions using the new plate tectonics concepts to replace the existing models. Her new explanations were supported with easily understandable diagrams, which are widely recognized and still in use.

Tanya continues to be an expert on the tectonics of western North America and on plate kinematics including the northeastern Pacific, with her marine geophysics work and her ability to integrate these data sets. With the increasing improvement in studies of the Pacific Ocean floor and its plate tectonic history, she synthesized a variety of marine geophysical observations to produce a tectonic map of the seafloor features of the NE Pacific (Atwater & Severinghaus, DNAG, 1989). Although later surveys filled some data gaps, this work still remains a standard now, 30 years later. Tanya interpreted the plate and microplate history revealed by this map, to examine the geological consequences such as slab gaps and provide further linkages with advances in onland tectonics (Atwater, DNAG, 1989).

Driven by her enthusiasm about these advances, Tanya turned her plate tectonic results into animations featuring an accurate, quantified history of plate motions and the related tectonic deformation. She established a web site and visualization center (http://emvc.geol.ucsb.edu) accessible to everyone, from senior scientists to the general public. Her animations and her publications, along with her inspiring teaching and the many field trips she has led for educators and non-specialists, constitute a lasting legacy that helps all of us understand and visualize the marvels of plate tectonics.