ADDITIONAL DATA FROM THE
1980 NORTHERN KENTUCKY EARTHQUAKE
(from Fall 1981 Ohio Geology)
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The earthquake of July 27, 1980, centered in northeastern Kentucky near the community of Sharpsburg, has been the most extensively studied seismic event in the north central United States. Two U.S. Geological Survey preliminary reports Open-File Report 80-1242, by M. G. Hopper and B. G. Reagor (1980), and Open-File Report 81-198, by B. G. Reagor, C. W., Stover, and M. G. Hopper (1981).
The earthquake, which was felt over an area of 600,000 sq. km, was assigned the following data:
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Origin time: |
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18 52 21.8 UTC (2:52 p.m. Eastern Daylight Time) |
| Latitude: |
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38.174°N |
| Longitude: |
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83.907°W |
| Depth: |
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8 km |
| Magnitude: |
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5.2 mb (body wave), 4.7 MS (surface wave) |
Maximum Modified
Mercalli intensity: |
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VII, Maysville, Kentucky |
Questionnaires were distributed by the U.S. Geological Survey to postmasters within a 700-km radius of the epicenter in order to assess the distribution of intensities during the earthquake.
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Generalized isoseismal map of the northern Kentucky earthquake of July 27, 1980 (modified from Reagor, Stover, and Hopper, 1981).
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In addition, onsite inspections for damages were conducted by U.S. Geological Survey personnel and individuals from other institutions in more than 100 communities. The result of these investigations is the accompanying isoseismal map, which demonstrates what was immediately apparent from media reports--the earthquake of July 27, 1980, was felt over a wide area. It is interesting to note that many of the higher intensities associated with the shock were concentrated along river valleys, areas commonly associated with thick alluvial sediments.
Reagor, Stover, and Hopper (1981) noted that the ground shaking, estimated to have had a duration of 15-45 seconds, caused widespread damage at the relatively low Modified Mercalli intensity of VI. In almost all cases, however, the observed damages in most areas consisted of cracking and displacement of bricks in chimneys. Inspection revealed that the majority of these chimneys were on older homes and the mortar between the bricks was weak or nearly completely weathered away. New, well-built chimneys in the same area as damaged ones appeared to have survived the shock with no damage.
As a final comment on the July 27, 1980, earthquake, it should be noted that if instrumental locations had been unavailable the epicenter of this event, based upon observed intensities, would have been placed at Maysville, Kentucky--about 50 km north of the actual epicenter. Information such as this points out the need for caution in assessing historic seismicity with only noninstrumental locations as a guide.
Last update March 03, 2003
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