Plate tectonics - the discovery that the Earth's surface is composed of a mosaic of rigid plates in motion, and that most significant events such as earthquakes and volcanic eruptions occur along the plate boundaries ? is the single most important theory about how he Earth works. If plates are truly rigid, it follows that where three plates meet, the sum of their motions must be zero, but observations clearly demonstrate that this condition is not met. This unresolved problem is of fundamental importance to our understanding of plate tectonics. One possible explanation is that the shapes of plates are slightly modified by thermal contraction as they age. This project has the aim of testing that hypothesis by quantifying the effects of the thermal contraction in a re-evaluation of the Pacific-Cocos-Nazca and Pacific-North America plate circuits. The results will contribute to our understanding ofht e workings of the Earth. The project will support a young investigator, and a graduate student, and the results will be shared with students in their coursework and through educational outreach.
