Coseismic changes in the kinetic rotational energy of the Earth from 1976 to 2019

Abstract

SUMMARY The energy changes corresponding to the axis and speed of the Earth’s rotation are the polar motion energy, ΔEpm and the spinning energy, ΔEss. Here we develop an explicit approach to compute the coseismic ΔEpm and ΔEss based on a spherical-Earth elastic dislocation theory. We estimate the cumulative changes induced by global major earthquakes from 1976 to 2019 using the derived expression. The results show that the rate of ΔEpm and ΔEss is 0.45 × 1012 and 0.20 × 1019 J −1, corresponding to 0.01 MW (1 MW = 106 Watt) and 0.06 TW (1 TW = 1012 Watt), respectively. The χ2 test shows that global earthquakes tend to strongly increase the spinning energy rather than the polar motion energy. Comparing the coseismic rotational energy to the coseismic gravitational energy and the radiated seismic-wave energy induced by every single event, we found that coseismic rotational energy is distinctly at least 7.6 times larger than the radiated seismic-wave energy, demonstrating the importance of rotational energy in the energy budget of the faulting.