Electronic Supplement to
Semiannual Earthquake Periodicity

by Patrick H. McClellan

Table S2. M ≥ 6.4 Mainshocks (n = 26) Included in the Southern-California-Region Sample and Their Phases in the Semiannual Cycle

Date Time, GMT (hh:mm:ss.ss)* Latitude (°) Longitude (°) Magnitude Phase Source§
9 January 1857 16:24:99.99 36.20 −120.80 7.90 0.611 UCERF2
21 July 1952 11:52:14.5400 34.9582 −118.998 7.50 0.659 UCERF3
24 February 1892 07:20:99.99 32.55 −115.65 7.30 0.863 UCERF2
28 June 1992 11:57:34.1300 34.2000 −116.437 7.28 0.537 UCERF3
4 April 2010 22:40:41.7700 32.2163 −115.300 7.19 0.082 UCERF3
16 October 1999 09:46:44.1300 34.5940 −116.271 7.12 0.127 UCERF3
4 November 1927 13:50:53.00 34.60 −120.90 7.10 0.230 UCERF2
19 May 1940 04:36:40.5000 32.8442 −115.381 6.90 0.319 UCERF3
9 February 1890 12:06:99.99 33.40 −116.30 6.80 0.783 UCERF2
21 April 1918 22:32:25.00 33.75 −117.00 6.80 0.169 UCERF2
29 June 1925 14:42:16.00 34.30 −119.80 6.80 0.539 UCERF2
9 February 1956 14:32:41.9100 31.8320 −116.231 6.80 0.779 UCERF3
25 December 1899 12:25:99.99 33.80 −117.00 6.70 0.516 UCERF2
17 January 1994 12:30:55.3900 34.2130 −118.537 6.65 0.655 UCERF3
9 April 1968 02:28:58.3900 33.1798 −116.103 6.60 0.105 UCERF3
9 February 1971 14:00:41.9200 34.4160 −118.370 6.60 0.780 UCERF3
22 December 2003 19:15:56.2400 35.7005 −121.100 6.55 0.500 UCERF3
15 October 1979 23:16:53.9100 32.6673 −115.359 6.51 0.124 UCERF3
12 April 1885 04:05:99.99 36.20 −120.80 6.50 0.122 UCERF2
10 April 1947 15:58:5.1100 34.9828 −116.531 6.50 0.108 UCERF3
24 November 1987 13:15:56.7100 33.0150 −115.852 6.50 0.343 UCERF3
31 December 1934 18:45:43.9200 32.1800 −115.175 6.42 0.548 UCERF3
22 July 1899 20:32:99.99 34.30 −117.50 6.40 0.665 UCERF2
3 March 1901 07:45:99.99 36.00 −120.50 6.40 0.901 UCERF2
11 March 1933 01:54:9.3400 33.6308 −117.999 6.40 0.944 UCERF3
19 March 1954 09:54:27.8300 33.2985 −116.081 6.40 0.990 UCERF3

“Northern” and “southern” California regions are delimited at latitude 36.5° N.

* 99 denotes the time unit value is unavailable.

† Magnitude type as given in the source.

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

§ Source is the catalog version from which earthquake record was taken (UCERF2, Felzer and Cao, 2008; UCERF3, Felzer, 2013).

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