20 Aftershocks Rumble Illinois, Indiana
St. Louis Dispatch
April 21, 2008
St. Louis Dispatch
At least five small aftershocks to Friday's earthquake rumbled through Southern Illinois this weekend, including a moderate quake measuring 4.5 on the Richter scale at 12:38 a.m. this morning.
This morning's earthquake was located about 5 miles from Mount Carmel, Ill., according to the U.S. Geological Survey, National Earthquake Information Center. Mount Carmel is about 131 miles from St. Louis, but was felt at least as far west as O'Fallon, Mo.
The previous aftershock occured 1:42 a.m. and again at 4:34 a.m. Sunday and measured 2.8 and 2.3 on the Richter scale.
Those earlier tremors on Saturday and Sunday, which hit in Bellmont and Mount Carmel, all measured between 1.3 and 2.8. Aftershocks are defined as occurring after the main shock and within a few kilometers of it.
Although a 4.5 magnitude aftershock struck Friday morning, hours after the 5.2 quake, most aftershocks tend to have a magnitude of less than 3.
"Usually, they're not felt," said Angel Gutierrez, a geophysicist with the U.S. Geological Survey in Golden, Colo. "It's kind of like when there's a big truck on the road, and there's that little rumble."
Gutierrez said the Geological Survey doesn't issue predictions, but that it's likely the tremors will continue for about a week after Friday's quake, or possibly for as long as two weeks.
AFTERSHOCKS
Mag. 2.2 April 21 07:58:46 38.450 -87.880 17.3 8 km (5 mi) NNE of Bellmont, IL
Mag. 4.5 April 21 05:38:30 38.473 -87.823 10.0 8 km (5 mi) NW of Mount Carmel, IL
Mag. 2.3 April 20 10:34:26 38.440 -87.900 16.9 6 km (4 mi) N of Bellmont, IL
Mag. 1.7 April 20 05:31:42 38.450 -87.880 14.2 8 km (5 mi) NNE of Bellmont, IL
Mag. 2.8 April 20 05:02:42 38.440 -87.850 16.3 8 km (5 mi) WNW of Mount Carmel, IL
Mag. 2.8 April 19 16:55:17 38.440 -87.900 14.9 6 km (4 mi) N of Bellmont, IL
Mag. 1.7 April 19 12:45:38 38.450 -87.910 15.4 7 km (5 mi) N of Bellmont, IL
Mag. 1.3 April 19 09:46:44 38.440 -87.850 14.4 8 km (5 mi) WNW of Mount Carmel, IL
Mag. 2.7 April 19 03:05:53 38.440 -87.890 14.1 6 km (4 mi) NNE of Bellmont, IL
Mag. 4.6 April 18 15:14:16 38.478 -87.869 10.0 11 km (7 mi) NNE of Bellmont, IL
Mag. 2.6 April 18 11:55:58 38.440 -87.890 11.2 6 km (4 mi) NNE of Bellmont, IL
Mag. 1.2 April 18 11:25:26 38.450 -87.880 15.4 8 km (5 mi) NNE of Bellmont, IL
Mag. 1.5 April 18 10:57:47 38.430 -87.920 17.3 5 km (3 mi) N of Bellmont, IL
Mag. 2.2 April 18 10:46:24 38.440 -87.880 17.8 7 km (4 mi) NNE of Bellmont, IL
Mag. 1.6 April 18 10:44:11 38.450 -87.850 15.9 8 km (5 mi) WNW of Mount Carmel, IL
Mag. 2.1 April 18 10:37:26 38.480 -87.850 14.2 10 km (6 mi) NW of Mount Carmel, IL
Mag. 3.4 April 18 10:36:33 38.460 -87.860 17.8 9 km (6 mi) NNE of Bellmont, IL
Mag. 1.9 April 18 10:06:06 38.440 -87.880 19.2 7 km (4 mi) NNE of Bellmont, IL
Mag. 2.2 April 18 10:04:00 38.450 -87.860 13.2 8 km (5 mi) NNE of Bellmont, IL
Mag. 2.6 April 18 09:59:31 38.469 -87.795 10.0 6 km (4 mi) NNW of Mount Carmel, IL
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