Earthquakes
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Ohio Earthquakes..................... Although most people do not think of Ohio as an Earthquake state, at least 120 earthquakes with epicenters in Ohio have been felt since 1776. In addition, a number of earthquakes with origins outside Ohio have been felt in the state. Most of these earthquakes have been felt only locally and have not caused damage or injuries. However, at least 14 moderate size earthquakes have caused minor damage in Ohio. Fortunately, no deaths and only a few minor injuries have been recorded for these events. Ohio is on the periphery of the New Madrid Seismic Zone, an area in Missouri and adjacent states that was the site of the largest earthquake sequence to occur in historical times in the continental United States. Four great earthquakes were part of a series at New Madrid in 1811 and 1812. These events were felt throughout the eastern United States and were of sufficient intensity to topple chimneys in Cincinnati. Some estimates suggest that these earthquakes had magnitudes in the range of 8.0. A major earthquake centered near Charleston, South Carolina, in 1886 was strongly felt in Ohio. More recently, an earthquake with a Richter magnitude of 5.3 centered at Sharpsburg, Kentucky in 1980 was strongly felt throughout Ohio and caused minor to moderate damage in communities near the Ohio River in southwestern Ohio. Earthquake Regions................. Three areas of the state appear to be particularly susceptible to seismic activity. Northeastern Ohio (including Lake County) has experienced at least 20 "felt" earthquakes since 1836. Most of these events were small and caused little or no damage. However, an earthquake on January 31, 1986, strongly shook Ohio and was felt in 10 other states and southern Canada. This event had a magnitude of 5.0 and caused minor damage, including broken windows and cracked plaster, in the epicenter area of Lake and Geauga counties. Seismic Risk............................... Seismic risk in Ohio and the eastern United States in general, is difficult to evaluate because earthquakes are generally infrequent in comparison to plate-margin areas such as California. Also, active faults do not reach the surface in Ohio and therefore cannot be mapped without the aid of expensive subsurface techniques. A great difficulty in predicting large earthquakes in the eastern United States is that recurrence intervals (time between large earthquakes) is commonly very long, on the order of hundreds or even thousands of years. Earthquake risk in the eastern United States is further compounded by the fact that seismic waves tend to travel very long distances. The relatively brittle and flat lying sedimentary rocks of this region tend to carry these waves throughout an area of thousands of square miles for even a moderate-sized earthquake. Damaging ground motion would occur in an area about 10 times larger than a California earthquake of comparable intensity. Earthquake Preparedness......................... Large earthquakes are so infrequent in the eastern United States that most people do not perceive a risk and are therefore unprepared for a damaging event. Simple precautions such as bolting bookcases to the wall, strapping water heaters to the wall, putting latches or bolts on cabinet doors and maintaining an emergency supply of canned food (with can opener), drinking water and other essentials can prevent both loss and hardship. Earthquake insurance is commonly available in Ohio for a nominal fee on most homeowners policies. Below is the Modified Mercalli Scale used for measuring the severity of quakes:
For more information, check out this site: http://www.earthquake.usgs.gov/eqcenter/recenteqsus/Quakes/quakes_big.php |
Send mail to
cheral.white@lakecountyohio.gov with
questions or comments about this web site.
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