Hi All. I have often wondered if a swarm of small quakes was an indication of a much larger quake to occur. I did a little search of areas where we don’t see quakes all that often just to see what I could find.

As far as I can tell there is no reliable way of telling if one quake is the main event or a foreshock. However a quake swarm might be an indication that a much larger quake is on the way. A swarm doesn’t always mean that a much larger event is on the way, but it is an area to watch.

About 20 hours prior to the Hector Mine quake there was a small swarm of quakes. I did a search of the area and found that there had never been a swarm in that area before. As a matter of fact quakes were far and few between. I felt that there could very well be a larger quake on the way, but never thought it would be as big as it was.

I did a search on some areas in and around the Bay Area to see what I could find in the way of activity before a large quake.

Two areas in particular have always intrigued me. They are the quake swarm in area of Petaluma, California, and the area of Mount Lewis, which is located just to the east of San Jose, California.

This catalog is for the Mount Lewis quake. The radius on this search is one mile. I started the search in 1976 and ended it with the M>5.7 quake. The radius for this search was one mile.

catalog=ANSS
start_time=1976/03/31,00:00:00
end_time=1986/03/31,12:00:00
minimum_magnitude=0.1
maximum_magnitude=10
event_type=E
delta=0 km to 1.6 km from (37.4788,-121.6858)
Date Time Lat Lon Depth Mag Magt Nst Gap Clo RMS SRC Event ID
----------------------------------------------------------------------------------------------
1976/04/04 19:57:53.85 37.4827 -121.6870 8.37 1.17 Md 10 118 11 0.03 NC -1029335
1976/06/30 16:46:18.81 37.4840 -121.6922 8.05 2.10 Md 28 116 10 0.06 NC -1030280
1976/07/01 06:02:32.35 37.4828 -121.6955 7.50 2.13 Md 29 114 10 0.06 NC -1030290
1976/07/02 01:35:41.66 37.4852 -121.6898 8.71 1.72 Md 17 117 10 0.03 NC -1030299
1976/10/18 14:49:27.35 37.4847 -121.6828 7.38 1.40 Md 14 165 11 0.03 NC -1031947
1977/01/01 01:44:51.51 37.4910 -121.6777 7.30 2.08 Md 18 125 12 0.05 NC -1033053
1977/05/21 04:40:37.84 37.4812 -121.6882 5.40 1.31 Md 16 118 10 0.07 NC -1035218
1978/07/20 01:03:45.26 37.4858 -121.6803 7.78 1.22 Md 13 122 11 0.02 NC -1041130
1978/08/30 21:59:36.09 37.4880 -121.6902 6.14 1.53 Md 15 117 11 0.03 NC -1041992
1978/12/19 14:44:57.13 37.4885 -121.6870 8.49 0.95 Md 7 118 11 0.01 NC -1043810
1980/07/31 06:42:32.98 37.4710 -121.6923 1.90 1.06 Md 20 59 4 0.05 NC -1054728
1981/07/13 23:42:26.96 37.4880 -121.6895 6.53 2.08 Md 21 56 3 0.07 NC -1065538
1982/01/27 05:05:13.59 37.4700 -121.6995 5.83 1.57 Md 47 38 11 0.11 NC -1071588
1982/01/28 15:38:56.71 37.4715 -121.6908 5.04 2.52 Md 61 39 11 0.10 NC -1071636
1982/02/03 23:54:25.27 37.4845 -121.6698 5.82 1.05 Md 9 111 2 0.07 NC -1071805
1983/03/11 18:04:38.13 37.4870 -121.6800 5.20 0.96 Md 14 67 9 0.03 NC -1089029
1983/06/17 22:50:33.62 37.4878 -121.6937 6.78 2.33 Md 58 63 4 0.07 NC -1097054
1983/06/20 09:34:18.12 37.4882 -121.6917 7.00 0.85 Md 6 102 4 0.01 NC -1097211
1983/07/01 23:02:28.74 37.4898 -121.6875 7.90 1.94 Md 25 96 9 0.08 NC -1097895
1984/05/01 07:44:26.41 37.4732 -121.6793 5.57 0.40 Md 9 81 10 0.01 NC 17337
1984/05/01 23:32:47.36 37.4658 -121.6935 4.06 0.88 Md 10 65 4 0.03 NC 17247
1984/05/01 23:38:53.46 37.4683 -121.6942 2.84 1.79 Md 35 32 4 0.05 NC 17248
1984/06/22 16:10:59.67 37.4708 -121.6945 3.68 1.28 Md 9 72 4 0.01 NC 21340
1984/06/24 16:41:10.44 37.4662 -121.6895 4.93 0.82 Md 7 192 3 0.01 NC 21471
1984/07/03 06:48:51.08 37.4742 -121.6860 9.19 0.93 Md 12 120 3 0.02 NC 21995
1984/07/05 12:35:30.60 37.4853 -121.6945 8.74 0.56 Md 7 112 4 0.01 NC 22143
1984/07/11 00:28:21.05 37.4700 -121.6948 4.01 1.08 Md 14 52 4 0.02 NC 22503
1984/07/11 04:39:46.78 37.4680 -121.6952 3.91 0.83 Md 11 55 4 0.03 NC 22518
1984/07/11 10:40:49.41 37.4678 -121.6947 3.98 0.92 Md 13 54 4 0.03 NC 22528
1984/07/24 10:41:45.80 37.4745 -121.6935 3.67 0.84 Md 12 70 4 0.03 NC 23790
1984/07/24 10:44:34.60 37.4748 -121.6942 3.57 0.86 Md 13 70 4 0.03 NC 23791
1984/07/28 15:28:00.18 37.4797 -121.6687 9.45 0.83 Md 13 61 1 0.02 NC 24614
1984/08/27 10:36:48.68 37.4837 -121.7000 2.86 0.40 Md 8 113 4 0.02 NC 26350
1984/08/29 16:56:01.53 37.4867 -121.6947 8.69 0.83 Md 9 115 9 0.01 NC 26766
1984/09/01 22:53:41.59 37.4752 -121.6988 8.06 0.79 Md 8 202 4 0.02 NC 26944
1984/09/02 20:54:29.32 37.4847 -121.6907 6.78 0.83 Md 18 61 3 0.04 NC 27026
1984/10/11 06:30:27.70 37.4843 -121.6970 9.20 0.89 Md 19 54 4 0.02 NC 29838
1984/10/31 03:58:54.94 37.4900 -121.6933 6.81 2.04 Md 61 39 4 0.04 NC 30999
1984/11/04 08:00:05.40 37.4855 -121.6968 9.09 1.09 Md 18 57 4 0.02 NC 31240
1984/11/04 08:25:29.68 37.4847 -121.6970 9.18 0.84 Md 17 61 4 0.02 NC 31241
1984/12/02 06:43:03.60 37.4857 -121.6958 8.87 0.40 Md 9 112 4 0.02 NC 33066
1984/12/08 16:51:36.42 37.4870 -121.6967 9.35 0.83 Md 10 111 9 0.02 NC 33657
1984/12/17 04:40:43.13 37.4873 -121.6970 9.05 0.80 Md 12 88 4 0.02 NC 34549
1984/12/17 19:20:24.26 37.4882 -121.6915 6.51 0.91 Md 12 88 4 0.02 NC 34605
1985/04/15 22:37:59.71 37.4867 -121.6905 7.24 0.71 Md 5 111 3 0.02 NC -1127395
1985/05/02 08:30:19.34 37.4855 -121.6915 5.95 1.22 Md 25 60 4 0.03 NC 47070
1985/05/11 03:56:15.14 37.4867 -121.6903 7.25 0.89 Md 20 60 3 0.02 NC 47830
1985/06/05 20:37:52.80 37.4860 -121.6912 7.23 2.40 Md 62 39 4 0.04 NC 49046
1985/06/29 08:17:42.56 37.4850 -121.6902 7.44 0.95 Md 10 93 9 0.01 NC 50401
1985/07/12 22:57:00.66 37.4683 -121.6908 5.63 1.45 Md 26 39 10 0.04 NC 51020
1985/07/16 17:40:51.25 37.4838 -121.6728 8.45 0.95 Md 10 99 9 0.02 NC 51229
1985/08/01 00:20:20.18 37.4848 -121.6895 7.58 0.73 Md 6 112 3 0.02 NC -1130169
1985/09/24 05:10:00.47 37.4855 -121.6865 8.37 1.51 Md 33 40 3 0.03 NC 55698
1985/09/24 05:10:15.70 37.4858 -121.6865 8.35 1.21 Md 20 60 3 0.02 NC 55729
1985/09/24 05:24:30.75 37.4857 -121.6860 8.84 0.90 Md 13 63 3 0.01 NC 55700
1985/09/24 06:57:28.22 37.4857 -121.6867 8.78 0.82 Md 10 111 3 0.02 NC 55702
1985/09/24 07:19:55.87 37.4870 -121.6870 8.50 0.76 Md 12 66 3 0.02 NC 55705
1985/09/24 07:21:29.80 37.4882 -121.6873 9.65 3.46 Md 87 41 3 0.07 NC 55728
1985/09/24 07:25:08.63 37.4838 -121.6877 8.81 2.33 Md 71 40 3 0.05 NC 55706
1985/09/24 07:36:59.17 37.4865 -121.6855 8.13 0.87 Md 13 62 3 0.01 NC 55707
1985/09/24 07:44:41.74 37.4835 -121.6865 8.78 1.03 Md 17 59 3 0.02 NC 55708
1985/09/24 11:28:31.76 37.4835 -121.6845 7.86 0.71 Md 5 113 9 0.01 NC -1131696
1985/09/24 16:07:02.71 37.4877 -121.6867 8.59 0.98 Md 16 66 3 0.02 NC 55721
1985/09/24 18:11:21.39 37.4840 -121.6887 8.59 1.00 Md 12 65 3 0.02 NC 55758
1985/09/24 19:27:57.33 37.4870 -121.6877 8.31 1.00 Md 11 66 3 0.01 NC 55765
1985/09/24 20:07:40.72 37.4842 -121.6872 8.15 1.68 Md 39 40 3 0.03 NC 55767
1985/09/25 21:33:43.35 37.4825 -121.6858 8.48 1.20 Md 16 57 3 0.02 NC 55811
1985/10/05 10:24:00.76 37.4833 -121.6868 8.87 1.58 Md 47 41 3 0.04 NC 56365
1985/10/05 18:40:01.13 37.4818 -121.6872 8.58 1.05 Md 10 61 3 0.02 NC 56255
1985/10/08 06:39:21.26 37.4845 -121.6863 9.08 1.17 Md 21 47 3 0.02 NC 56473
1985/10/08 15:34:18.44 37.4822 -121.6862 9.19 0.93 Md 13 68 3 0.01 NC 56435
1985/10/09 09:36:21.99 37.4828 -121.6857 8.59 1.32 Md 42 41 3 0.03 NC 56542
1985/10/10 06:00:42.08 37.4748 -121.6703 8.78 2.06 Md 74 39 2 0.04 NC 56598
1985/10/12 16:18:52.31 37.4815 -121.6867 8.27 0.63 Md 5 209 9 0.01 NC -1132200
1985/10/17 12:16:04.18 37.4842 -121.6842 7.97 1.05 Md 20 61 3 0.02 NC 57137
1985/10/21 22:39:55.95 37.4817 -121.6870 9.13 0.96 Md 18 55 3 0.02 NC 57434
1985/10/26 15:25:42.44 37.4835 -121.6858 8.56 0.89 Md 13 67 3 0.02 NC 57692
1985/10/29 21:12:57.59 37.4835 -121.6845 8.32 0.71 Md 4 136 9 0.00 NC -1132594
1985/10/30 01:46:05.66 37.4873 -121.6873 8.46 1.21 Md 17 65 3 0.02 NC 57916
1985/10/30 08:58:55.06 37.4837 -121.6865 8.53 0.95 Md 12 60 3 0.02 NC 57931
1985/11/05 20:16:18.39 37.4773 -121.6702 10.71 1.30 Md 8 127 10 0.05 NC 58381
1985/11/18 12:18:49.05 37.4678 -121.6842 8.17 1.09 Md 8 75 3 0.01 NC 59351
1985/11/18 12:33:38.38 37.4675 -121.6863 8.53 0.97 Md 20 54 3 0.03 NC 59480
1985/11/20 11:35:24.84 37.4792 -121.6862 9.17 1.23 Md 40 40 3 0.02 NC 59496
1985/11/20 11:40:31.21 37.4790 -121.6847 9.02 0.83 Md 18 47 3 0.02 NC 59498
1985/11/23 17:25:48.45 37.4773 -121.6862 8.98 1.45 Md 43 40 3 0.03 NC 59758
1985/11/25 17:32:07.40 37.4842 -121.6917 8.63 1.08 Md 12 93 9 0.02 NC 59873
1985/12/02 06:45:04.32 37.4835 -121.6863 9.09 1.21 Md 20 59 3 0.02 NC 60312
1985/12/03 14:11:19.70 37.4827 -121.6875 8.75 0.74 Md 12 105 3 0.02 NC 60477
1985/12/03 21:59:03.55 37.4830 -121.6858 8.39 0.77 Md 4 135 9 0.00 NC -1133487
1985/12/09 19:24:45.13 37.4817 -121.6863 9.46 1.19 Md 25 47 3 0.03 NC 60983
1985/12/17 19:51:35.34 37.4880 -121.6865 8.74 0.71 Md 5 109 3 0.00 NC -1133950
1985/12/30 11:55:01.02 37.4797 -121.6850 7.44 1.00 Md 11 120 10 0.02 NC 62457
1986/01/03 01:13:57.90 37.4783 -121.6932 7.09 1.06 Md 12 115 10 0.02 NC 62648
1986/01/03 21:55:12.89 37.4852 -121.6895 8.72 1.05 Md 19 64 3 0.02 NC 62843
1986/01/09 11:09:55.98 37.4862 -121.6903 7.70 1.76 Md 57 64 3 0.04 NC 63170
1986/01/14 21:31:48.07 37.4860 -121.6900 7.74 1.04 Md 17 85 3 0.03 NC 63547
1986/02/01 10:39:09.53 37.4863 -121.6862 8.08 1.27 Md 25 65 9 0.02 NC 65258
1986/02/11 02:25:51.06 37.4812 -121.6992 8.75 1.30 Md 9 115 10 0.02 NC 66119
1986/02/12 18:57:25.29 37.4818 -121.6758 6.35 1.02 Md 12 125 9 0.02 NC 66378
1986/02/13 14:44:18.70 37.4735 -121.6713 1.51 0.60 Md 7 246 10 0.06 NC 66412
1986/03/06 19:21:10.00 37.4708 -121.6748 6.70 0.76 Md 7 98 11 0.01 NC -1136483
1986/03/20 15:42:57.08 37.4752 -121.6860 8.14 1.49 Md 34 52 3 0.04 NC 68396
1986/03/22 18:26:01.64 37.4762 -121.6832 7.78 0.74 Md 4 136 10 0.00 NC -1136798
1986/03/23 01:37:24.96 37.4842 -121.6857 8.55 1.05 Md 21 61 3 0.02 NC 68536
1986/03/24 01:44:48.51 37.4827 -121.6857 9.17 1.27 Md 28 58 3 0.03 NC 68598
1986/03/24 01:46:04.92 37.4813 -121.6868 9.28 1.33 Md 29 54 3 0.02 NC 68599
1986/03/24 01:46:22.04 37.4808 -121.6867 9.13 1.21 Md 20 54 3 0.02 NC 68656
1986/03/24 01:54:41.43 37.4802 -121.6862 9.41 2.81 Md 77 40 3 0.05 NC 68600
1986/03/24 02:14:38.26 37.4812 -121.6862 9.09 1.18 Md 18 94 9 0.02 NC 68601
1986/03/24 02:26:21.73 37.4823 -121.6877 8.99 2.49 Md 74 41 3 0.04 NC 68602
1986/03/24 02:50:15.10 37.4832 -121.6865 8.70 0.95 Md 17 94 9 0.02 NC 68603
1986/03/24 02:52:05.67 37.4827 -121.6862 8.97 1.19 Md 18 58 3 0.02 NC 68604
1986/03/24 03:39:39.56 37.4778 -121.6867 9.20 0.94 Md 12 94 10 0.01 NC 68812
1986/03/24 05:06:00.49 37.4807 -121.6865 8.87 1.56 Md 42 53 3 0.03 NC 68607
1986/03/24 06:29:07.87 37.4777 -121.6865 8.60 1.72 Md 54 40 3 0.04 NC 68611
1986/03/25 03:16:25.06 37.4823 -121.6857 8.76 1.07 Md 14 57 3 0.01 NC 68665
1986/03/31 04:04:59.86 37.4792 -121.6880 8.90 2.55 Md 74 65 3 0.05 NC 68948
1986/03/31 11:55:39.80 37.4788 -121.6858 9.17 5.70 ML 84 65 3 0.06 NC 68932

This catalog search is in the area of Petaluma. The radius on this search is one mile. As you can see it is almost identical to the Mount Lewis quake, but in this case there was no large quake.

catalog=ANSS
start_time=1981/01/01,00:00:00
end_time=1986/03/31,12:00:00
minimum_magnitude=0.1
maximum_magnitude=10
event_type=E
delta=0 km to 1.6 km from (38.2962,-122.6122)
Date Time Lat Lon Depth Mag Magt Nst Gap Clo RMS SRC Event ID
----------------------------------------------------------------------------------------------
1981/12/13 11:32:32.33 38.3012 -122.6085 8.88 2.36 Md 26 51 11 0.06 NC -1070277
1981/12/18 14:41:44.77 38.3008 -122.6105 8.70 3.42 Md 36 49 11 0.09 NC -1070433
1981/12/18 17:30:06.59 38.2985 -122.6078 6.81 2.10 Md 13 69 6 0.13 NC -1070438
1981/12/20 07:40:56.29 38.3050 -122.6180 4.15 2.54 Md 23 49 8 0.16 NC -1070476
1981/12/20 07:41:49.69 38.3027 -122.6172 9.91 3.45 Md 42 47 11 0.14 NC -1070477
1981/12/20 07:43:57.45 38.3020 -122.6093 6.01 2.26 Md 21 76 7 0.10 NC -1070478
1981/12/20 09:21:03.45 38.2970 -122.6110 0.49 1.48 Md 6 89 7 0.06 NC -1070480
1981/12/20 10:25:29.95 38.3003 -122.6133 6.89 2.97 Md 40 50 7 0.14 NC -1070484
1981/12/20 10:31:03.84 38.3028 -122.6123 2.75 1.20 Md 4 142 7 0.00 NC -1070486
1981/12/20 13:45:12.75 38.2987 -122.6112 0.36 1.40 Md 9 79 7 0.06 NC -1070492
1981/12/20 15:29:55.88 38.3002 -122.6092 7.62 3.12 Md 45 49 7 0.15 NC -1070496
1981/12/20 15:42:33.10 38.2988 -122.6130 0.84 1.21 Md 6 90 7 0.02 NC -1070497
1981/12/20 18:16:53.15 38.2980 -122.6085 1.70 1.48 Md 6 90 7 0.01 NC -1070503
1981/12/20 23:33:24.81 38.2910 -122.6182 0.04 2.50 Md 20 56 7 0.14 NC -1070509
1981/12/20 23:59:52.06 38.2940 -122.6165 0.03 1.78 Md 8 87 7 0.04 NC -1070510
1981/12/21 02:55:47.97 38.2962 -122.6162 0.03 1.80 Md 8 87 7 0.11 NC -1070517
1981/12/21 07:13:30.18 38.3045 -122.6113 0.83 1.26 Md 6 76 7 0.04 NC -1070524
1981/12/21 08:08:56.19 38.3043 -122.6097 0.70 1.60 Md 5 117 7 0.01 NC -1070525
1981/12/21 12:33:49.70 38.2987 -122.6122 2.41 1.33 Md 7 81 7 0.03 NC -1070529
1981/12/23 05:14:20.37 38.2958 -122.6107 1.44 1.24 Md 9 81 7 0.05 NC -1070560
1981/12/24 07:49:43.25 38.2998 -122.6113 2.75 1.51 Md 5 148 7 0.04 NC -1070603
1981/12/24 08:49:43.13 38.3063 -122.6082 2.52 1.57 Md 4 115 17 0.05 NC -1070604
1981/12/27 21:45:44.91 38.2972 -122.6120 1.30 1.51 Md 7 92 7 0.02 NC -1070727
1981/12/27 23:43:28.47 38.2948 -122.6138 2.79 1.50 Md 8 123 7 0.05 NC -1070734
1982/01/06 08:14:42.53 38.3048 -122.6107 5.35 1.85 Md 18 68 7 0.16 NC -1071002
1982/01/06 18:23:22.35 38.3018 -122.6000 6.00 2.13 Md 13 80 6 0.08 NC -1071018
1982/01/09 11:04:02.75 38.3018 -122.6140 0.03 1.61 Md 16 78 7 0.12 NC -1071084
1982/01/09 11:09:17.01 38.3038 -122.6063 0.27 1.33 Md 10 76 7 0.02 NC -1071085
1982/01/10 01:35:42.37 38.3027 -122.6143 6.21 2.37 Md 34 35 7 0.15 NC -1071101
1982/01/10 02:41:37.23 38.3003 -122.6083 4.97 1.62 Md 15 79 7 0.10 NC -1071102
1982/01/10 06:06:07.35 38.2973 -122.6080 6.47 2.23 Md 29 57 6 0.11 NC -1071109
1982/01/10 12:49:52.15 38.3065 -122.6137 0.02 1.09 Md 6 95 7 0.08 NC -1071123
1982/01/14 11:37:52.15 38.3012 -122.6157 3.62 1.21 Md 6 91 7 0.03 NC -1071254
1982/04/16 01:35:03.31 38.3017 -122.6068 3.45 1.28 Md 7 132 7 0.05 NC -1073767
1982/05/05 08:27:51.38 38.2948 -122.6053 6.65 2.43 Md 29 75 6 0.14 NC -1074181

This search is the area around the 1989 Loma Prieta quake. The radius on the search is 7.5 miles. The current theory about this quake is that the 2 M>5.0+ plus quakes loosened the fault up enough for the fault to move.

catalog=ANSS
start_time=1988/01/01,00:00:00
end_time=1989/10/21,00:00:00
minimum_magnitude=0.1
maximum_magnitude=10
event_type=E
delta=0 km to 12 km from (37.0632,-121.8802)
Date Time Lat Lon Depth Mag Magt Nst Gap Clo RMS SRC Event ID
----------------------------------------------------------------------------------------------
1988/01/21 14:06:42.12 37.0972 -121.8920 10.03 1.31 Md 13 109 5 0.06 NC 111212
1988/03/15 04:37:51.60 37.0218 -121.7775 0.64 0.31 Md 4 214 4 0.00 NC -1155523
1988/04/02 04:07:01.22 37.0595 -121.7485 12.79 0.70 Md 12 116 2 0.03 NC 114985
1988/04/16 06:48:26.39 37.1202 -121.8573 9.99 0.72 Md 15 61 2 0.02 NC 115744
1988/04/17 08:35:28.54 37.1328 -121.9090 12.37 0.76 Md 11 76 5 0.04 NC 115777
1988/04/21 20:07:35.53 37.1330 -121.9087 11.96 0.87 Md 12 97 5 0.05 NC 116035
1988/04/25 12:15:03.52 37.0660 -121.8627 15.59 0.98 Md 14 108 5 0.05 NC 116186
1988/05/14 18:27:07.56 37.1538 -121.8222 5.21 0.77 Md 11 95 2 0.04 NC 117194
1988/05/28 11:12:19.52 37.1357 -121.8503 7.78 0.70 Md 9 114 2 0.05 NC 118086
1988/05/28 11:35:59.62 37.1413 -121.9122 10.47 0.72 Md 11 83 4 0.03 NC 118087
1988/06/06 18:43:38.51 37.1508 -121.9270 10.54 0.86 Md 10 84 2 0.04 NC 118458
1988/06/11 14:57:12.89 37.1400 -121.9027 12.53 0.98 Md 12 89 4 0.05 NC 118707
1988/06/12 20:25:00.58 37.1262 -121.9150 12.92 1.24 Md 13 66 5 0.03 NC 118798
1988/06/17 10:02:39.65 37.0680 -121.8995 15.58 0.65 Md 9 105 5 0.03 NC 119166
1988/06/18 06:32:10.08 37.0475 -121.8227 6.36 0.29 Md 4 186 1 0.00 NC -1156781
1988/06/20 14:28:18.96 37.1463 -121.9195 11.51 1.01 Md 21 49 3 0.08 NC 119303
1988/06/27 18:43:22.32 37.1268 -121.8962 13.15 5.30 ML 90 46 5 0.10 NC 10139668
1988/06/27 18:44:23.23 37.1380 -121.8997 11.42 2.92 Mx 18 70 5 0.03 NC 10087452
1988/06/27 18:53:59.84 37.1483 -121.9015 8.69 0.70 Md 6 142 4 0.03 NC 119658
1988/06/27 22:34:53.40 37.1543 -121.9145 9.21 1.25 Md 25 97 2 0.09 NC 119659
1988/06/29 22:43:24.08 37.1408 -121.9200 11.09 0.96 Md 11 98 3 0.03 NC 119713
1988/06/30 03:08:44.90 37.1243 -121.8845 11.01 2.35 Md 76 44 5 0.08 NC 119724
1988/07/05 21:04:34.57 37.1397 -121.9235 10.29 1.08 Md 8 86 3 0.02 NC 119958
1988/07/06 03:31:56.14 37.1480 -121.9070 11.08 1.14 Md 14 61 3 0.06 NC 119974
1988/07/06 09:01:55.44 37.1490 -121.9270 9.39 0.94 Md 12 70 2 0.04 NC 119981
1988/07/10 14:25:22.17 37.1383 -121.9175 11.43 1.67 Md 38 50 4 0.07 NC 120157
1988/08/21 17:05:19.21 37.1487 -121.9237 12.53 1.59 Md 41 49 2 0.08 NC 122646
1988/08/28 07:33:09.33 37.1123 -121.9902 11.85 0.78 Md 8 126 7 0.02 NC 122950
1988/08/28 17:13:26.52 37.1315 -121.8830 10.43 1.18 Md 27 44 4 0.05 NC 122966
1988/09/04 18:12:28.43 37.1340 -121.9200 13.30 1.16 Md 18 72 4 0.05 NC 123280
1988/09/05 16:22:17.35 37.1488 -121.9147 8.85 0.74 Md 9 91 3 0.04 NC 123381
1988/09/21 23:49:53.74 37.1163 -121.9090 9.06 0.82 Md 11 72 6 0.04 NC 124097
1988/09/22 13:31:34.46 37.1155 -121.9173 9.87 0.50 Md 6 141 6 0.06 NC 124142
1988/10/10 16:02:05.20 37.1230 -121.8775 11.24 1.60 Md 42 43 4 0.08 NC 125255
1988/10/22 10:49:10.84 37.1277 -121.9137 13.87 1.02 Md 17 71 5 0.05 NC 126401
1988/10/23 14:50:23.62 37.1348 -121.9088 9.63 0.58 Md 7 127 4 0.04 NC 125687
1988/11/03 00:07:28.06 37.0415 -121.8007 5.57 0.45 Md 5 138 1 0.01 NC -1159291
1988/11/12 07:21:36.10 37.1370 -121.8998 11.31 0.79 Md 6 101 5 0.01 NC 126887
1988/11/14 00:21:31.06 37.0708 -121.8642 5.00 0.50 Md 4 196 5 0.01 NC -1159470
1988/11/22 13:09:50.49 37.1462 -121.9093 11.90 0.87 Md 19 63 3 0.06 NC 127452
1988/12/10 19:24:54.27 37.1188 -121.8827 11.99 1.14 Md 14 79 4 0.05 NC 128457
1988/12/28 09:22:54.78 37.1550 -121.9230 9.23 0.61 Md 8 116 2 0.05 NC 129303
1988/12/31 23:11:31.54 37.0177 -121.8677 4.78 0.70 Md 11 140 2 0.03 NC 129447
1989/02/17 12:13:26.01 37.1245 -121.7740 10.51 0.74 Md 12 51 6 0.03 NC 131492
1989/03/13 02:30:54.09 37.1440 -121.9003 12.21 1.00 Md 12 101 4 0.04 NC 132758
1989/03/16 02:26:19.30 37.1263 -121.7720 10.44 0.75 Md 10 136 7 0.04 NC 132896
1989/03/19 03:24:01.47 37.1245 -121.7733 10.68 0.90 Md 12 51 6 0.03 NC 133028
1989/03/22 12:44:11.33 37.1252 -121.7708 10.14 0.84 Md 14 48 6 0.05 NC 133243
1989/03/27 14:11:44.16 37.1252 -121.7748 10.81 0.78 Md 18 48 6 0.04 NC 133522
1989/04/06 04:39:43.01 37.1242 -121.8787 11.20 0.67 Md 10 93 4 0.03 NC 134032
1989/04/09 07:47:12.01 37.1263 -121.7725 9.90 0.84 Md 14 49 6 0.05 NC 134204
1989/04/19 12:50:53.31 37.1270 -121.7740 10.20 0.75 Md 12 49 6 0.03 NC 134819
1989/05/22 12:39:06.01 37.1553 -121.9318 10.94 1.16 Md 25 50 2 0.07 NC 136558
1989/05/23 14:00:21.06 37.0020 -121.8073 14.61 1.15 Md 21 79 2 0.05 NC 136668
1989/06/06 01:09:41.30 37.1077 -121.8375 10.07 1.17 Md 25 57 0 0.04 NC 137502
1989/06/27 05:41:27.38 37.0340 -121.8035 13.96 0.92 Md 19 57 2 0.04 NC 138955
1989/06/28 05:06:12.29 37.0325 -121.8067 14.24 0.86 Md 14 71 2 0.03 NC 139023
1989/06/29 14:31:46.50 37.0320 -121.8053 14.15 1.43 Md 31 41 2 0.06 NC 139110
1989/07/04 07:55:28.85 37.1367 -121.9022 10.14 0.70 Md 8 106 5 0.02 NC 139405
1989/07/11 00:41:42.34 37.0342 -121.8178 8.72 0.53 Md 12 77 2 0.17 NC 139748
1989/07/15 23:22:29.81 37.0327 -121.8043 13.85 0.83 Md 20 57 2 0.04 NC 140088
1989/07/22 09:22:15.35 37.0697 -121.8575 5.45 0.30 Md 8 162 5 0.02 NC 140521
1989/07/28 01:16:53.27 37.1195 -121.8972 11.02 0.84 Md 12 71 6 0.06 NC 140977
1989/08/07 17:40:34.17 37.1543 -121.9278 12.14 1.00 Md 25 54 2 0.06 NC 141703
1989/08/08 08:13:27.36 37.1458 -121.9282 14.23 5.40 ML 87 51 3 0.10 NC 10089897
1989/08/08 08:44:09.66 37.1430 -121.9257 13.41 4.30 ML 92 51 3 0.10 NC 10089900
1989/08/08 08:48:33.05 37.1532 -121.9240 12.25 1.01 Md 21 49 2 0.06 NC 141956
1989/08/08 08:52:34.33 37.1498 -121.9208 11.95 1.22 Md 34 49 2 0.08 NC 141923
1989/08/08 08:57:51.90 37.1505 -121.9162 12.19 1.09 Md 34 48 3 0.08 NC 141782
1989/08/08 08:59:03.57 37.1492 -121.9202 11.74 1.13 Md 30 49 2 0.09 NC 141799
1989/08/08 12:30:52.45 37.1570 -121.9385 13.33 2.16 Md 74 51 2 0.07 NC 141858
1989/08/08 13:09:13.52 37.1492 -121.9215 11.79 2.09 Md 56 49 2 0.08 NC 141960
1989/08/08 15:25:43.71 37.1585 -121.9392 12.96 1.41 Md 38 51 1 0.05 NC 141966
1989/08/09 02:12:05.68 37.1580 -121.9185 12.95 0.85 Md 10 105 2 0.07 NC 141852
1989/08/09 06:42:24.91 37.1578 -121.9375 13.10 1.39 Md 42 51 1 0.07 NC 141895
1989/08/09 15:10:17.40 37.1513 -121.9352 12.30 1.01 Md 20 51 2 0.06 NC 141902
1989/08/09 16:44:20.50 37.1442 -121.9308 12.31 2.43 Md 65 52 3 0.09 NC 142045
1989/08/09 16:46:17.33 37.1557 -121.9375 11.04 0.92 Md 12 116 2 0.06 NC 142078
1989/08/09 17:43:53.86 37.1503 -121.9342 11.87 0.46 Md 9 69 2 0.05 NC 141907
1989/08/09 19:28:57.04 37.1478 -121.9323 11.69 1.44 Md 38 51 2 0.07 NC 142047
1989/08/09 21:42:58.86 37.1572 -121.9345 13.48 1.75 Md 48 51 1 0.10 NC 141926
1989/08/10 00:30:35.10 37.1552 -121.9380 13.71 1.83 Md 50 51 2 0.06 NC 141932
1989/08/10 00:59:53.82 37.1540 -121.9402 12.07 1.83 Md 50 52 2 0.09 NC 141935
1989/08/14 02:40:50.58 37.1597 -121.8378 5.11 0.76 Md 12 92 1 0.02 NC 142193
1989/08/15 11:10:42.79 37.0675 -121.7507 11.45 0.73 Md 16 60 3 0.06 NC 142279
1989/08/20 16:55:32.53 37.1617 -121.8317 4.28 1.24 Md 22 71 2 0.07 NC 142634
1989/08/21 14:00:06.72 37.1570 -121.9293 12.00 1.00 Md 8 157 1 0.03 NC 142705
1989/08/22 19:00:00.49 37.1488 -121.9203 11.42 0.76 Md 9 100 3 0.04 NC 142775
1989/08/24 11:06:04.03 37.1395 -121.8870 14.10 0.90 Md 8 109 4 0.01 NC 142880
1989/08/30 03:52:25.53 37.1207 -121.9100 13.44 0.91 Md 20 52 6 0.05 NC 143286
1989/08/31 10:53:42.11 37.1235 -121.9217 15.59 0.90 Md 16 65 5 0.04 NC 143346
1989/09/03 23:13:14.46 37.1297 -121.8895 11.82 1.02 Md 22 52 5 0.07 NC 143524
1989/09/04 21:21:33.91 37.1565 -121.9405 13.76 1.58 Md 40 52 2 0.06 NC 143580
1989/09/07 11:45:47.49 37.0938 -121.9125 11.71 0.53 Md 12 131 7 0.03 NC 143703
1989/09/08 03:46:50.11 37.1592 -121.9397 14.68 2.07 Md 60 51 1 0.08 NC 143728
1989/09/09 09:14:17.11 37.1470 -121.9122 11.74 0.99 Md 23 48 3 0.07 NC 143789
1989/09/10 04:27:01.51 37.1472 -121.9170 11.81 0.84 Md 13 86 3 0.03 NC 143907
1989/09/11 11:16:16.10 37.1567 -121.9408 14.12 3.14 Md 82 52 2 0.08 NC 143914
1989/09/14 14:27:18.19 37.1535 -121.9127 10.88 0.81 Md 7 150 2 0.03 NC 144033
1989/09/26 21:31:41.81 37.1500 -121.9197 12.88 1.08 Md 19 85 2 0.06 NC 144654
1989/10/10 02:10:39.78 37.1275 -121.8917 12.51 1.27 Md 29 46 5 0.07 NC 145229
1989/10/18 00:04:15.20 37.0362 -121.8802 17.29 7.00 ML 79 91 1 0.08 NC 216859

This search is also for the Loma Prieta quake. The radius for this is 2.5 miles. As you can see there was no tight swarm in the area of the epicenter.

catalog=ANSS
start_time=1988/01/01,00:00:00
end_time=1989/10/18,00:05:00
minimum_magnitude=0.1
maximum_magnitude=10
event_type=E
delta=0 km to 04 km from (37.0632,-121.8802)
Date Time Lat Lon Depth Mag Magt Nst Gap Clo RMS SRC Event ID
----------------------------------------------------------------------------------------------
1988/01/21 14:06:42.12 37.0972 -121.8920 10.03 1.31 Md 13 109 5 0.06 NC 111212
1988/04/25 12:15:03.52 37.0660 -121.8627 15.59 0.98 Md 14 108 5 0.05 NC 116186
1988/06/17 10:02:39.65 37.0680 -121.8995 15.58 0.65 Md 9 105 5 0.03 NC 119166
1988/11/14 00:21:31.06 37.0708 -121.8642 5.00 0.50 Md 4 196 5 0.01 NC -1159470
1989/07/22 09:22:15.35 37.0697 -121.8575 5.45 0.30 Md 8 162 5 0.02 NC 140521
1989/10/18 00:04:15.20 37.0362 -121.8802 17.29 7.00 ML 79 91 1 0.08 NC 216859

I’m not sure what I have learned from this search, but I do know that a tight swarm can be an indication that a larger quake is on the way. It doesn’t mean that there will be a large quake each and every time, but it is something to keep in mind. Take Care…Don in creepy town