## 3 Results
Boundary conditions are written as:  
\[W_{i,\;1}^{k}=W_{i,\;2}^{k}, \tag{3}\]  
\[W_{i,\;L}^{k}=\frac{W_{i,\;L-1}^{k}}{1+k_{i}\Delta x}, \tag{4}\]  
\[W_{i,\;L+1}^{k}=W_{i,\;L}^{k},\;t_{k}\text{ during interseismic phase}, \tag{5}\]  
\[W_{i,\;L+1}^{k}=W_{i,\;L+2}^{k},\;t_{k}\text{ during postseismic phase}. \tag{6}\]  
Similar to the original single-segment model, the evolution of the block system described by expressions (1-2), (5-6) is controlled by the conditions for dumping the accumulated elastic energy in the form of an abrupt decrease in compressional stresses at \(t_{eq}^{i}\), corresponding to earthquakes, occurring when the frontal block reaches the threshold energy \(\epsilon_{cr}\):  
\[\sigma_{i}^{1}\left(x,\;t_{eq}^{i}+1\right)=q^{1}\sigma_{i}^{1}\left(x,\;t_{ eq}^{i}\right), \tag{7}\]  
\[\sigma_{i}^{2}\left(x,\;t_{eq}^{i}+0\right)=q^{2}\sigma_{i}^{1}\left(x,\;t_{ eq}^{i}-0\right), \tag{8}\]  
Note that this condition is equivalent to an instantaneous change in displacement, with some coefficients that take into account the differences in the elastic modulus between the frontal and rear segments. The specific time instants of the earthquakes, \(t_{eq}^{i}\), are determined from the expression:  
\[\epsilon_{i}\left(t_{eq}^{i}\right)=\frac{E}{2H_{m}}\int_{0}^{l}H(x)\left( \frac{\partial w_{i}\left(t_{eq}^{i}\right)}{\partial x}\right)^{2}dx=\epsilon _{cr} \tag{9}\]  
To demonstrate the main features of the model kinematics, we have performed series of simulations, showing the evolution of the model over a 500-year time interval (Figure 10). Figure 10: Displacement variations \(W(x,t)\), simulated with a two-segment model for a series of points within the rear-segment blocks (\(x=150\), \(160\), \(175\), and \(225\) km), calculated for a typical set of model parameters (see Table 1). An important feature of the model behavior is the existence of oceanward motion of the entire rear segment following every subsequent earthquake (a postseismic or aftershock stage). Modeling of this oceanward motion is of great importance for better assessment of the duration of the seismic cycle and the time moment of the transition of subduction zone to the next seismic cycle. The duration of the aftershock phase depends on the rheological parameters of the medium and can reach up to 50 years in the rear and central part of the rear block and a few years at its frontal edge. Our tests also helped us determine the limits for the viscous parameters of the model. We found that the model behaves in an expected way (accumulation of elastic stress occurs in a reasonable time range (See Table 1)) for the viscosity of the contact layer and the asthenosphere lying in the range of 0.1-1 \(\times\) 10\({}^{19}\) Pa-s. Lower viscosity (less than 10\({}^{18}\) Pa-s) causes numerical instability of the solution. In the case of higher viscosity (of the order of 10\({}^{20}\) Pa-s), the slow (at around 1 cm/year) oceanward motion persists all over the cycle, and the rear block does not experience any continent-ward motion at all. The obtained estimates for model viscous parameters are consistent with the earlier results lying in the range 5 \(\times\) 10\({}^{17}\)-5 \(\times\) 10\({}^{19}\) Pa-s [35; 36; 37; 38; 39; 40].