Maybe you think I am getting excruciatingly single minded, but even though we try to think and talk about other things we are pretty much every day reminded of the earthquake by after-quakes. Yesterday was no exception. At 10:40 pm we were rocking gently in our bed.

As you can see in the images above the area where we live (purple blob in the right image) is located on the boarder between a green (3 in magnitude) and yellow area (4 in magnitude). On the 12th floor that shakes you a bit but it doesn’t move any furnitures, and once you feel there is no more energy going into the shakes they really don’t bother you that much.

To give some perspective, the red area in the left image is in the upper 6 in magnitude and about 100+ km away from where we live. Traveling through the ground the energy has reduced to around 3-4 in magnitude. Compare that to Friday’s earthquake of 8.9-9.0 in magnitude about 100 km outside of Sendai that you can find almost at the upper end of the right map, 300+ km away from where we live. From epicenter the energy traveled 350+ km to Tokyo and was reduced to 5-6+ in magnitude.

Note that the magnitudes in the images from the JMA is in the JMA Intensity Scale. Which measures the degree of shaking at a point on the earth (the colored areas and dots in JMA graphics) compared to the Richter scale that measures the local magnitude and quantifies the energy with a single number such as 8.9 or 9.0.