MD-T chart

MD-T chart is time series graph of MD (product of Magnitude and Depth) . 

This is the example of MD-T chart in 三陸沖(Sanriku-oki) as below,

Next chart is limited of the maximum value of Vertical axis as 100 [M・km]. Before M9.0, the yellow blank area of shallow area was observed in MD-T chart. The blank area seems to be the sign of M9.0.   

D value is used as class value to avoid MD=0 when D=0[km]. The class value of 0km is 1km.