<P> Other significant earthquakes in Ohio include: one of magnitude 4.8 near Lima on September 19, 1884; one of magnitude 4.2 near Portsmouth on May 17, 1901; and one of 5.0 in LeRoy Township in Lake County on January 31, 1986, which continued to trigger 13 aftershocks of magnitude 0.5 to 2.4 for two months . </P> <P> The most recent earthquake in Ohio of any appreciable magnitude occurred on December 31, 2011, at 3: 05pm EST . It had a magnitude of 4.0, and its epicenter was located approximately 4 kilometres northwest of Youngstown (41 ° 7 ′ 19.1994" N 80 ° 41 ′ 2.3994" W ﻿ / ﻿ 41.121999833 ° N 80.683999833 ° W ﻿ / 41.121999833; - 80.683999833), near the Trumbull / Mahoning county border . </P> <P> The Ohio Seismic Network (OhioSeis), a group of seismograph stations at several colleges, universities, and other institutions, and coordinated by the Division of Geological Survey of the Ohio Department of Natural Resources, maintains an extensive catalog of Ohio earthquakes from 1776 to the present day, as well as earthquakes located in other states whose effects were felt in Ohio . </P> <Table> <Tr> <Th_colspan="10"> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> Largest cities or towns in Ohio Source: </Th> </Tr> <Tr> <Th> </Th> <Th> Rank </Th> <Th> Name </Th> <Th> County </Th> <Th> Pop . </Th> <Th> </Th> </Tr> <Tr> <Td> Columbus Cleveland </Td> <Td> </Td> <Td> Columbus </Td> <Td> Franklin </Td> <Td> 860,090 </Td> <Td> Cincinnati Toledo </Td> </Tr> <Tr> <Td> </Td> <Td> Cleveland </Td> <Td> Cuyahoga </Td> <Td> 385,809 </Td> </Tr> <Tr> <Td> </Td> <Td> Cincinnati </Td> <Td> Hamilton </Td> <Td> 298,800 </Td> </Tr> <Tr> <Td> </Td> <Td> Toledo </Td> <Td> Lucas </Td> <Td> 278,508 </Td> </Tr> <Tr> <Td> 5 </Td> <Td> Akron </Td> <Td> Summit </Td> <Td> 197,542 </Td> </Tr> <Tr> <Td> 6 </Td> <Td> Dayton </Td> <Td> Montgomery </Td> <Td> 140,599 </Td> </Tr> <Tr> <Td> 7 </Td> <Td> Parma </Td> <Td> Cuyahoga </Td> <Td> 79,425 </Td> </Tr> <Tr> <Td> 8 </Td> <Td> Canton </Td> <Td> Stark </Td> <Td> 71,885 </Td> </Tr> <Tr> <Td> 9 </Td> <Td> Youngstown </Td> <Td> Mahoning </Td> <Td> 64,312 </Td> </Tr> <Tr> <Td> 10 </Td> <Td> Lorain </Td> <Td> Lorain </Td> <Td> 63,647 </Td> </Tr> </Table>

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