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We propose a data mining method to extract physical phenomena from the ground vibration velocity fluctuation (GVF) which is a daily observed weak signal and has no specific waveform. Our aim is to detect any traces of the return of ground motion to its normal state after earthquakes, and the evolution of ground motion towards earthquakes in the GVF. We focus on the GVF recorded near the epicenter of the magnitude 9 Great East Japan Earthquake (GEJE). Although the GVF can be discussed in the framework of the master equation which represents the thermodynamics of a stochastically fluctuating non-equilibrium system, the relation between the thermodynamic parameters and seismology-related phenomena is hardly known. So, we introduce cellular automata (CA) to analogically interpret the physical phenomena of interest as thermodynamic parameters, and show the thermodynamic equivalence between GVF and CA. These CA-derived thermodynamic parameters are then expected to deliver physical phenomena similar to those of the target when evaluated on the GVF data. In the demonstrated example of data mining, the stress relaxation signal immediately after GEJE is discovered from the recorded GVF data by deriving the thermodynamic parameters representing the stress relaxation of CA and evaluating these thermodynamic parameters for the recorded GVF data. Furthermore, the elastic rigidity and viscosity of the underground structures are estimated from the stress relaxation signal. The novelty of this study lies in drawing attention to the GVF, and combining standard techniques of CA with GVF through the use of the master equation. [ABSTRACT FROM AUTHOR]

In Northeast Japan, it remains a puzzle to reconcile the mismatch between long-term (geological) uplift and late-interseismic and coseismic subsidence associated with the 2011 Tohoku earthquake. To explain this mismatch between different periods, we modeled the entire megathrust earthquake cycle in the Northeast Japan arc using a simple dislocation model with a two-layered lithosphere-asthenosphere structure in which we account for viscoelastic relaxation in the asthenosphere and tectonic erosion. The model behaves differently when the rupture stops within the lithosphere and when it cuts through the lithosphere to reach the asthenosphere. It is possible to explain the mismatch in the case where the rupture stops within the lithosphere. In the early interseismic stage, the viscoelastic response to the megathrust earthquake dominates and can compensate for late-interseismic and coseismic subsidence. In contrast, the late-interseismic stage is dominated by the locking effect with the steady slip below the rupture area. Tectonic erosion explains up to about half of the long-term uplift by landward movement of arc topography. The rest of the long-term uplift may be attributed to indirect effects of internal deformation in the arc. [ABSTRACT FROM AUTHOR]