Today there were three: magnitudes 4.6, 5.4 and 5.2. All were far enough from Tokyo that I didn’t feel them.

The number of quakes has definitely gone done a lot since the big one hit in March. The daily energy release from earthquakes has also gone way down.

This graph shows the daily release in energy since 3/11.

The red line shows the daily release of energy.

On March 11, an almost incomprehensible 2.1 EJ (2.1 quintillion joules) of energy was released in the 78 earthquakes that hit that day. By comparison, the energy released in the nuclear bomb used at Hiroshima released 63 trillion joules, so the energy released by the 3/11 earthquakes was over 30 thousand times as large. It was enough to slightly tilt the earth on its axis and shift the entire continent of Honshu.

Since the number of earthquakes have dropped greatly (yellow line) the daily release of energy has also fallen greatly. But even today, 12.4 trillion joules of energy was released in the three earthquakes. Fortunately that was distributed in 3 quakes in three different areas of the country and there was no reported damage.

doug