The entropy production rate (EPR), which is a property of thermodynamically non-equilibrium systems, occasionally decreases sharply in the seismic process of the Great East Japan Earthquake (GEJE) of magnitude 9. The decrease indicates a state change towards an equilibrium system where no time-dependent change occurs. The timing of the EPR decrease is found to be clearly different from that of earthquakes of magnitude less than 9, but close to the timing of the earthquake of magnitude 9. In the GEJE process, EPR is calculated from the binarized velocity deviation of ground vibrations found to be equivalent to velocity. The equivalence attributes to that the transformation between them does not change the α-tremor which is the curvature of the Fourier amplitude spectrum of the velocity, and that an arbitrary ground vibration can be defined by α-tremor. The α-tremor is a noise. However, it is associated with microearthquakes whose epicenter is close to the GEJE epicenter, and is an important component of the GEJE process. By binarizing the velocity deviation with “0” and “1”, the vibrational state at a time interval can be defined as the number of clusters of “1” at the time interval. Once the thermodynamic state is defined, the master equation that explains the time evolution of the state can be written down and the EPR is mathematically formulated. EPR is evaluated for ground vibration data acquired every 0.05 seconds from 2006 to 2018 at a seismic station 188 km from the GEJE epicenter.