The figure and the list below are from the
LCSN:
Date Time Lat Long Depth Magnitude
year-mo-dy hh:mm:sec (N) (W) (km) (Mc)
--------------------------------------------------
Lancaster County, PA
1972-12-08 03:00:32.5 40.150 76.220 4 0.0
1978-07-16 06:39:39.6 39.900 76.220 0 0.0
1984-04-19 04:54:55.1 39.946 76.323 7 2.9
1984-04-23 01:36:02.0 39.946 76.323 4 4.1
1984-04-23 02:46:00.5 39.946 76.323 10 2.5
1994-01-16 03:03:31.3 40.532 76.247 4 2.0
1995-03-11 21:10:16.0 40.100 76.400 5 2.7
1997-11-14 03:44:11.7 40.164 76.276 6 3.0
2000-03-22 20:48:00.0 40.070 76.300 1 1.8
2000-10-05 23:33:59.0 40.080 76.300 7 2.0
2001-07-17 14:41:20.2 39.937 76.340 1 1.8
2008-12-27 05:04:34.5 40.114 76.403 3 3.4
Adams County, PA
1994-05-26 17:21:58.2 39.950 77.187 11 2.8
Dillsburg, York County, PA
1997-06-16 05:43:16.6 40.098 76.967 5 1.9
2008 (21 events)
2008-10-05 22:36:48.1 40.054 76.967 2 2.0
2008-10-06 01:06:13.4 40.120 77.025 0 1.2
2008-10-06 06:15:38.4 40.069 76.992 0 1.1
2008-10-19 08:21:22.7 40.080 77.019 5 1.9
2008-10-19 08:22:07.3 40.078 76.963 5 2.1
2008-10-19 08:26:20.5 40.168 77.038 5 1.2
2008-10-19 08:28:09.0 40.087 76.998 5 1.5
2008-10-19 08:58:31.7 40.092 76.974 3 1.8
2008-10-19 09:06:01.5 40.091 77.018 5 1.0
2008-10-19 09:08:20.7 40.056 76.962 5 0.8
2008-10-19 09:08:44.3 40.092 76.987 5 1.1
2008-10-19 09:17:34.8 40.100 77.009 5 1.7
2008-10-19 09:49:19.1 40.095 77.002 5 1.0
2008-10-19 09:49:51.7 40.075 76.973 5 1.5
2008-10-19 09:50:11.4 40.091 76.989 5 1.6
2008-10-20 00:08:26.6 40.159 77.107 5 1.2
2008-10-20 00:14:03.9 40.075 77.005 5 1.1
2008-10-20 02:16:02.4 40.090 76.984 5 1.5
2008-10-23 15:55:32.3 40.068 76.962 5 1.2
2008-11-07 04:07:03.0 40.096 77.006 1 1.4
2008-12-31 05:34:08.8 40.107 77.003 1 2.1
2009 (3 events)
2009-04-22 13:21:14.1 40.073 77.002 1 1.1
2009-04-23 22:26:04.4 40.085 76.998 1 2.4
2009-04-24 05:36:48.8 40.064 77.026 1 2.9
See any patterns here? Maybe I'll try that next.
Posts
The figure and the list below are from the LCSN:
The obvious overall pattern is an association with the Mesozoic Gettysburg rift basin, and, in Lancaster County, the "narrow neck" between the Gettysburg and Newark Basins. Even the 1984 earthquake in southern Lancaster County fits this pattern because its epicenter was close to n early Jurassic diabase dike, indicating that Mesozoic fracturing of the crust extends at least that far outside the basin itself. As for the details of the Dillsburg swarm, it is important to realize that the posted epicenters and depths were found by the regional network, and, therefore, have significant uncertainties attached to them. When results are available from the temporary local network that Lamont operated for several weeks in the fall, we should see a much more detailed picture.
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