Earthquakes in Japan (last 7 days)

The sheer number of earthquakes that Japan has experienced over the last seven days is astounding, as is the difference in energy between the ‘smaller’ ones and the 8.9. The data is from the USGS. My thoughts are with the people of Japan.


  1. Joe Mako
    Mar 13, 2011

    This looks very nice, but there are a couple of things that I don’t understand:
    – What is the benefit of using the same color scale to represent two different measures on the same dashboard? Does red mean worse?
    – What is the axis for the tall depth sheet on the left?
    – When Showing Energy, why is there one with an energy of 1.413*10^18? I don’t know enough, but to me it seems to be an error in the underlying data.

    • Alex Kerin
      Mar 13, 2011

      Good criticism Joe. I believe the energy is correct – Magnitude is on a a log scale. The conversion is: log(Energy) = 4.8 + (1.5xMw), so 8.9 on the Richter is equivalent to 10^(4.8+1.5*8.9). I have left the colors as they are – red is worse for both scenarios – magnitude and the proximity to the surface. I added the axis back to the depth (km).

      • Alex Kerin
        Mar 14, 2011

        One thing I have found while looking further is that there seems to be some variations in the magnitude to energy to conversion – with a different constant and sometimes multiplier. With that said, the chart would look essentially the same.

  2. Calvin
    Mar 26, 2011

    Awesome blog post Alex. Helps to get a very clear visual understanding of the number, magnitude, and locations or earthquakes in Japan. Its extremely unfortunate what has happened there and my prayers are with those people as well. Thanks for providing this graph.


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