Electronic Supplement to
Semiannual Earthquake Periodicity

by Patrick H. McClellan

Table S21. Solar Semiannual (Ssa) Phase of M ≥ 7.8 Mainshocks North of 23.5° N (Tropic of Cancer) from 1 January 1900 to 13 February 2015

Date Time, UTC (hh:mm:ss.ss) Latitude (°) Longitude (°) Magnitude* Phase
28 March 1964 3:36:16 60.908 −147.339 9.3 0.041
11 March 2011 46:24.1 38.297 142.373 9 0.946
4 November 1952 16:58:30 52.623 159.779 8.9 0.237
4 February 1965 5:01:22 51.251 178.715 8.7 0.752
1 April 1946 12:29:01 53.492 −162.832 8.6 0.061
15 August 1950 14:09:34 28.363 96.445 8.6 0.791
9 March 1957 14:22:33 51.499 −175.626 8.6 0.937
2 March 1933 17:31:00 39.209 144.59 8.5 0.898
13 October 1963 5:17:59 44.872 149.483 8.5 0.108
3 February 1923 16:01:50 54.486 160.472 8.4 0.746
6 November 1958 22:58:09 44.479 148.485 8.4 0.246
9 July 1905 9:40:39 49.709 98.483 8.3 0.591
17 August 1906 0:11:10 51.853 178.18 8.3 0.796
16 December 1920 12:05:55 36.888 105.606 8.3 0.468
10 November 1938 20:18:49 55.178 −158.181 8.3 0.266
20 December 1946 19:19:10 33.116 135.895 8.3 0.488
4 October 1994 22:55.8 43.773 147.321 8.3 0.062
25 September 2003 50:06.4 41.815 143.91 8.3 0.013
15 November 2006 14:13.6 46.592 153.266 8.3 0.295
24 May 2013 44:49.0 54.892 153.221 8.3 0.348
5 June 1920 4:21:35 23.684 121.986 8.2 0.409
22 August 1949 4:01:18 53.673 −133.015 8.2 0.827
16 May 1968 0:49:02 40.86 143.435 8.2 0.303
11 August 1969 21:27:35 43.424 147.859 8.2 0.773
12 April 1910 0:22:24 25.911 123.973 8.1 0.115
7 September 1918 17:16:23 46.737 150.653 8.1 0.913
1 September 1923 2:58:00 35.4 139.2 8.1 0.877
7 December 1944 4:35:45 33.682 136.204 8.1 0.417
27 November 1945 21:56:54 24.927 63.601 8.1 0.362
4 March 1952 1:22:49 42.084 143.899 8.1 0.908
4 December 1957 3:37:53 45.189 99.368 8.1 0.397
15 January 1934 8:43:25 26.885 86.589 8 0.641
12 September 1946 15:17:23 24.054 95.666 8 0.941
20 March 1960 17:07:31 39.869 143.228 8 0.001
7 May 1986 47:10.9 51.52 −174.776 8 0.258
12 May 2008 6:28:01 31.2 103.9033 8 0.284
4 April 1905 0:49:59 32.636 76.788 7.9 0.074
15 June 1911 14:25:53 29.049 128.778 7.9 0.461
30 January 1917 2:45:40 56.136 163.168 7.9 0.721
10 August 1931 21:18:45 46.817 89.915 7.9 0.763
18 November 1941 16:46:32 32.095 131.949 7.9 0.311
25 November 1953 17:48:55 34.006 141.625 7.9 0.351
4 May 1959 7:15:47 53.257 159.732 7.9 0.236
26 May 1975 11:51.5 35.997 −17.649 7.9 0.355
30 November 1987 23:19.6 58.679 −142.786 7.9 0.377
3 December 1995 18:01:30 44.663 149.3 7.9 0.394
10 June 1996 03:35.5 51.564 −177.632 7.9 0.439
3 November 2002 22:12:41 63.517 −147.444 7.9 0.231
23 June 2014 53:09.7 51.8486 178.7352 7.9 0.511
22 December 1906 18:21:11 44.284 85.572 7.8 0.497
1 May 1915 5:00:10 48.361 155.162 7.8 0.217
8 November 1918 4:38:09 44.893 151.896 7.8 0.251
15 November 1921 20:36:43 36.202 70.711 7.8 0.295
7 March 1929 1:34:42 50.852 −169.753 7.8 0.922
17 December 1929 10:58:42 53.559 171.972 7.8 0.47
9 March 1931 3:49:00 40.572 142.398 7.8 0.931
7 January 1937 13:20:42 35.434 97.759 7.8 0.597
5 November 1938 8:43:24 36.966 142.09 7.8 0.236
26 December 1939 23:57:23 39.771 39.577 7.8 0.52
10 November 1940 1:39:05 45.708 26.563 7.8 0.266
29 March 1954 6:17:07 36.988 −3.612 7.8 0.043
10 July 1958 6:15:58 58.23 −136.712 7.8 0.596
2 July 1965 20:58:40 52.99 −167.739 7.8 0.558
28 February 1969 2:40:32 36.033 −10.613 7.8 0.885
5 December 1997 26:54.7 54.841 162.035 7.8 0.406
14 November 2001 26:10.0 35.946 90.541 7.8 0.29
17 November 2003 43:06.8 51.146 178.65 7.8 0.303
28 October 2012 04:08.8 52.788 −132.101 7.8 0.197

See Case S9 “Note: Modified U.S. Geological Survey Database” subsection for explanation of events
included in the April 2014 catalog search in Table S17 that are not included in the February 2015 search above.

* Magnitude type as given in ANSS catalog.

† Phase is the fraction of the cycle elapsed between bounding equinoxes.

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