9/56 YEAR CYCLE: OREGON EARTHQUAKES

The ensuing Pacific Northwest Seismograph Network listing contains the 22 Oregon quakes of magnitude 4.5 or greater. Of the total 20 quakes since 1930, 13 appeared in the 6.5 months beginning May 30 of those years in Table C, where as only 2.7 could have been expected by chance. If this was expanded to 12 months beginning May 30, some 14 events appeared in Table A (significant p < .001).


DATE-(UTC)-TIME   LAT(N) LON(W)   DEP  MAG QUAL COMMENTS
yy/mm/dd hh:mm:ss   deg.   deg.    km   Ml
1873/11/23 05:05:00  42.79N 124.50W   0.0 6.3   67.2 km SSW of Coos Bay, OR
1877/10/12 17:00:00  45.50N 122.50W   0.0 5.4   10.2 km ESE of Portland, OR
1930/07/19 02:38:00  45.00N 123.19W   0.0 5.0   14.5 km WNW of Salem, OR
1941/12/29 18:37:00  45.53N 122.62W   0.0 5.0    0.0 km   S of Portland, OR
1953/12/16 04:32:12  45.50N 122.69W   0.0 5.0    7.4 km WSW of Portland, OR
1957/11/17 06:00:29  45.29N 123.80W   0.0 5.0   17.7 km   S of Tillamook, OR
1960/11/08 11:36:23  45.04N 125.38W   0.0 5.0  114.9 km WNW of Newport, OR
1961/11/07 01:29:08  45.70N 122.86W   0.0 4.7   26.5 km  NW of Portland, OR
1962/11/06 03:36:43  45.60N 122.59W  18.0 5.5    8.3 km NNE of Portland, OR
1963/03/07 23:53:27  44.84N 123.41W  47.0 4.6   32.6 km WSW of Salem, OR
1968/05/30 00:35:58  42.33N 119.84W  22.0 5.1   15.7 km NNE of Adel, OR
1968/06/03 13:27:39  42.25N 119.80W  20.0 5.0    9.9 km  NE of Adel, OR
1968/06/04 02:34:14  42.24N 119.87W  25.0 4.6    5.6 km NNE of Adel, OR
1968/06/05 04:51:56  42.22N 119.98W  25.0 4.6    9.1 km WNW of Adel, OR
1976/04/13 00:47:14  45.07N 120.85W  15.0 4.6  DD  FELT   20.6 km ESE of Maupin, OR
1993/03/25 13:34:35  45.03N 122.60W  20.6 5.6  CB  FELT   23.0 km ESE of Woodburn, OR
1993/09/21 03:28:55  42.31N 122.02W  10.3 5.9  AD  FELT   22.7 km WNW of Klamath Falls, OR
1993/09/21 05:45:35  42.35N 122.05W  10.3 6.0  AD  FELT   23.6 km ESE of Mt McLoughlin, OR
1993/12/04 22:15:19  42.29N 122.00W   6.5 5.1  AB  FELT   20.2 km WNW of Klamath Falls, OR
2002/06/29 14:36:04  45.33N 121.68W   6.2 4.5  BB  FELT    4.5 km   S of Mt Hood, OR
2004/07/12 16:45:00  44.33N 124.48W  29.2 4.9  BD  FELT   48.4 km  SW of Newport, OR
2004/08/19 06:06:03  44.66N 124.30W  27.9 4.7  BD  FELT   19.9 km   W of Newport, OR

Table C 9/56 YEAR GRID & MAJOR OREGON QUAKES: 1930-2004 (=>mag 4.5)
												1937	1946
					1930 0719	1939	1948	1957 1117	1966	1975	1984	1993 0921 0921 1204	2002 0629
1941 1229	1950	1959	1968 0530 0603 0604 0605	1977	1986	1995	2004 0712 0819
The 56 year sequences in the table are each separated by an interval of 9 years. Years in bold contained Oregon earthquakes (mag =>4.5) in the 6.5 months beginning May 30 of those years in the table. Source of Raw Data: Pacific Northwest Seismograph Network