Analysis for the curve chart of distribution of epicenter (Magnitude)

The curve chart of the ,magnitude distribution in Iwate-oki Area including of Great East Japan Earthquake as below,

Just before Great East Japan Earthquake (M9.0), the frequency distribution curve of magnitude became almost negative quadratic function curve. The correlation coefficient (R^2) was 0.9281. It becomes 0.7697 now. M9.0 was irregular dot for these quadratic function curves. It seems to be similar with the exception of Gutenberg-Richter law in larger Magnitude zone.

The frequency distribution curves of magnitude has many patterns.

The curve chart of the ,magnitude distribution in Kumamoto region Area including of Great East Japan Earthquake as below, 

The top shape of the curve is sharper than one of quadratic function curve. The irregular plots are spread to the negative area of horizontal axis. Most of these epicenters were occurred in Aso region. So, these plots may be caused by volcanic activity of M't Aso(volcano). The irregular plots may be occurred by the difference of the earthquake mechanism.

There are other patterns like as multi peak curves, amorphous, etc. These difference should have the reasonable cause. It must be useful to solve the reasons.