For the majority of the aftershock sequenceds, the ETAS model has a smaller AIC value than the nonstationary Poisson mdels with the modified Omori intensity function, which suggests existence of clusters within the aftershock sequence. Most of the scatterplots between the maximum likelihood estimates of the characteristic parameters are seen to be either positively or negatively correlated. Clear positive correlations between the parameters of b, p of the least square method, are seen for the intraplate earthquakes, but that was not clear for interplate events except(b, D)

On the other hand, we estimated the P values using the ETAS model, and the fractal dimension D by the maximum likelihood. Thus, we investigated correlations between P and αvalue of the ETAS model, b, and the fractal dimension D. The contrasting correlation patterns are revealed between the estimated parameters for the intraplate and interplate earthquakes, except for the two pairs (b, D) and (α, p) in which similar correlation patterns are found.

We then focus our attention on these patterns as a source of interesting contrasts between the two earthquake groups, i.e. the intraplate and interplate events. In particular, the significant dependence of these parameters on the depth appears a key to understand the correlation pattern for interplate aftershocks, while a different interpretation is made for intraplate aftershocks because no dependence on depth is observed., 総研大甲第241号}, title = {Statistical Analyses of Aftershocks for the Relations Between Their Models in Time, Space, and Magnitude}, year = {} }