Based on eight published plate motion models, we separately estimated the net area changes of tectonic plates and the area change of the solid Earth surface over geological time using the Euler vectors of plates with determined boundaries. Then, under the context of a currently expanding Earth, we inferred the change rate of the Earth’s mean radius from the estimated net area changes. The results show that the total increases and decreases in the areas of different plates cannot be compensated. Specifically, the area of the Northern Hemisphere decreases while that of the Southern Hemisphere increases, but the net area of the solid Earth surface slightly increases in th computing period(0.01 Ma). For the latest NNRMORVEL56 plate motion model, the area of the Southern Hemisphere increases by 7802 km2 while the area of the Northern Hemisphere decreases by 7711 km~2. This indicates a net area increase of 91 km2 in the solid Earth surface corresponding to an expansion rate of 0.06 mm/a for the Earths mean radius.This result coincides with the slow rate of expansion derived from geodetic measurements and geophysical modeling.
the National Natural Science Foundation of China(Grant No.41474086 and 41704080)
the Basic Research Project of Institute of Earthquake Forecasting of China Earthquake Administration(Grant No.2018IES0402)
supported by Academia Sinica.
Corresponding author:Changyi Xu,Institute of Earthquake Forecasting,China Earthquake Administration,Beijing,China.E-mail address:email@example.com,an associate research fellow at Institute of Earthquake Forecasting,China Earthquake Administration.He received his Ph.D.in Geophysics from University of Chinese Academy of Sciences.His research focuses on mass migration in the Earth system,earthquake-induced changes in geodynamics,modeling and observations of co-/postseismic deformations;Xiao Yu is a master student at the University of Chinese Academy of Sciences.He received his B.S.from University of Science and Technology of China in 2016.His research focuses on dynamic modeling of plate motion;Dongping Wei is a professor at College of Earth and Planetary Sciences,University of Chinese Academy of Sciences.He received his Ph.D.in Geophysics from University of Tokyo in 1997.His research focuses on micro plate motion,subduction numerical modeling,data digging and analysis.