Earthquake Analysis

Below the results of analysis of all earthquakes in Japan in the period 18 November 2011 to March 1st 2013. Magnitudes (left column) were compared to shindou (shaking intensity - top row) using data from the JMA. This proves most lower magnitude earthquakes have lower shaking intensities, but high magnitude (6.0-6.9) earthquakes can also generate shindou 1 earthquakes. It also shows earthquakes with the high shindou of 5- can be generated by earthquakes with magnitudes ranging from 4 to 7. Less than 50% of all earthquakes of Magnitude 6 caused a shindou of 5- or 5+, and earthquakes with shindou 7 even failied to produce shindou 5+.

Mag.	6-	5+	5-	4	3	2	1
2	0	0	0	0	11	98	674
3	0	0	0	4	56	462	1278
4	0	0	3	33	191	376	271
5	0	5	20	51	30	31	26
6	0	7	3	4	5	1	3
7	0	0	2	1	1	0	0

Please note some data gaps have occurred and this does not capture all earthquakes up to shindou 3. In this period, there were no earthquakes with a magnitude higher than 7 or a shindou higher than 5+. The results are also visualized in the image below:

From these results the average shindou per magnitude was calculated. Since there is both a 5- and 5+ shindou, these values were both treated as if the value was 5.

Average shindou	Magnitude
1.15	2
1.33	3
1.99	4
3.11	5
3.74	6
4.25	7

Time for percentages! First the absolute number of earthquakes are listed again, with totals per magnitude and shindou. Next are the percentages relative to the total number of earthquakes. This is followed by the percentages relative to the shindou level and then relative to the magnitude. I hope this gives some perspective on the average earthquake in Japan, which has magnitude 3-3.9 and shindou 1. Please note that the shindou and magnitude are the highest values measured, and are not felt all across the country but are rather localized. 

Absolute
Magnitude	5+	5-	4	3	2	1	Total
2	0	0	0	11	98	674	783
3	0	0	4	56	462	1278	1800
4	0	3	33	191	376	271	874
5	5	20	51	30	31	26	163
6	7	3	4	5	1	3	23
7	0	2	1	1	0	0	4
Total	12	28	93	294	968	2252	3647

Percentage of total
Magnitude	5+	5-	4	3	2	1	Total
2	0.00	0.00	0.00	0.30	2.69	18.48	21.47
3	0.00	0.00	0.11	1.54	12.67	35.04	49.36
4	0.00	0.08	0.90	5.24	10.31	7.43	23.96
5	0.14	0.55	1.40	0.82	0.85	0.71	4.47
6	0.19	0.08	0.11	0.14	0.03	0.08	0.63
7	0.00	0.05	0.03	0.03	0.00	0.00	0.11
Total	0.33	0.77	2.55	8.06	26.54	61.75	100.00
3647

Percentage per shindou
Magnitude	5+	5-	4	3	2	1
2	0.00	0.00	0.00	3.74	10.12	29.93
3	0.00	0.00	4.30	19.05	47.73	56.75
4	0.00	10.71	35.48	64.97	38.84	12.03
5	41.67	71.43	54.84	10.20	3.20	1.15
6	58.33	10.71	4.30	1.70	0.10	0.13
7	0.00	7.14	1.08	0.34	0.00	0.00
Total	100	100	100	100	100	100

Percentage per magnitude
Magnitude	5+	5-	4	3	2	1	Total
2	0.00	0.00	0.00	1.40	12.52	86.08	100
3	0.00	0.00	0.22	3.11	25.67	71.00	100
4	0.00	0.34	3.78	21.85	43.02	31.01	100
5	3.07	12.27	31.29	18.40	19.02	15.95	100
6	30.43	13.04	17.39	21.74	4.35	13.04	100
7	0.00	50.00	25.00	25.00	0.00	0.00	100