[CEUS-earthquake-hazards] FYI: 70th Anniversary of Anna, Ohio, Earthquake -- Largest Recorded in Ohio

[Phyllis Steckel]

FYI:  The following article was published in the March 7, 2007, issue of the Port Clinton (Ohio) News-Herald.  

Phyllis Steckel, RG
Washington, Mo.
********

70th anniversary of largest Ohio earthquake March 9

      This week marks the 70th anniversary of the largest earthquake ever recorded in Ohio, according to the Ohio Department of Natural Resources. 

      March 2 and March 9, 1937, western Ohio experienced earthquakes that caused considerable damage in the Shelby County town of Anna, as well as surrounding communities, including Sidney and Wapakoneta. 


      The smaller of the two earthquakes, on March 2, is estimated to have had a magnitude of 4.9 and caused damage to chimneys and foundations in Anna. The earthquake on March 9, the largest ever recorded in Ohio, is estimated to have had a magnitude of 5.4 and damaged or knocked down nearly every chimney in the town. 

      Numerous buildings in Anna experienced cracks in foundations, walls and ceilings. Windows were broken; merchandise was knocked from store shelves. Monuments in local cemeteries rotated on their bases. Some area wells overflowed with water, while others appeared to dry up. 
      The March 9 earthquake was felt across 150,000 square miles, including parts of Indiana, Illinois, Kentucky, Michigan, Missouri, West Virginia, Pennsylvania and southern Canada. Workers on the Washington Monument felt the structure sway from the earthquake, a report said. 

      The town school in Anna suffered the most extensive property damage. The brick building was so badly cracked that it had to be torn down. Fortunately, the local school board had taken out an earthquake insurance policy in 1932, which helped to pay for a new building. 

      While the new school was under construction, classes resumed first in local homes, and later in barracks brought in by the Civilian Conservation Corps. 

      The Anna earthquakes of 1937 were the most significant and damaging to strike Ohio in modern times. Since 1776, scientists have noted 15 damaging earthquakes in the state. Most earthquakes occur in either the Anna Seismic Zone of western Ohio or the northeastern part of the state, east of Cleveland. However, damaging earthquakes have also occurred in Portsmouth and Pomeroy in southern Ohio. 

      The Anna earthquakes of 1937 remind Ohioans that damaging seismic incidents, although infrequent, can occur in the state. In 2006, the state experienced 16 earthquakes -- two in Lima in Allen County and 14 in Lake and Ashtabula counties. The largest, which shook the lakefront counties from Cleveland to Ashtabula on June 20, had a 3.8 magnitude. 

      The Ohio Seismic Network consists of 25 volunteer-operated seismograph stations coordinated by the ODNR Division of Geological Survey. The network continually monitors local and regional earthquake activity, helping define areas of potential seismic activity and evaluating seismic risk. Information is available from the Ohio Seismic Network's Web site at ohiodnr.com/ohioseis. 

     
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