Okay, but none of them are displayed on this graph. I would bet a paycheck that there were hundreds of quakes between 2.5 and 4.0; this graph implies there were none. That's all.

I find it very difficult to believe, just from the standpoint of probability, that there were precisely zero earthquakes between magnitude 2.5 and 4.0, as indicated by the comment.

Also, were the earthquakes evenly spaced in time, as the lines on the chart appear to be? This makes it appear that the quakes occurred exactly 19 minutes after the last one.