With the recent earthquakes in Haiti and Chile I have been thinking about the earthquake potential here in Ohio. Unlike Haiti and Chile, Ohio is not on the edge of a tectonic plate. But we still have an earthquake now and then. Several years ago, I found a USGS website with the capability to plot the location of historical earthquakes in a given geographical area. I created a map, shown above, for earthquakes in the eastern United States. The map at this link shows additional earthquakes in southeastern Canada… http://earthquakescanada.nrcan.gc.ca/historic-historique/map-carte-en.php
Human beings have an innate capacity for seeing patterns, sometimes even where there are none. Being human, I can’t escape that tendency. When I look at my map, I see two broad lines of earthquakes, one on each side of the Appalachian mountains and running roughly parallel to the eastern coast of the country. I speculate that these earthquakes occur on cracks and faults in the earth’s crust that are remnants of the collisions and breakups of supercontinents hundreds of millions of years ago. While most of the earthquakes on the map are minor, a number of them have caused structural damage, most notably to chimneys and other masonry structures. A few have been large. The 1811-1812 series of earthquakes in the region around New Madrid, Missouri are among the largest known earthquakes the conterminous United States. That includes California! While they occurred prior to the invention of the seismograph the magnitudes of two of those earthquakes are estimated to have been between 7.2 and 8.0. These and several other large historical earthquakes in the eastern United States and Canada are listed below.
The New Madrid series, including:
1811, December 16, 08:15 UTC. Northeast Arkansas Magnitude ~7.2 – 8.1
1811, December 16, 14:15 UTC, Northeast Arkansas
1812, January 23, 15:00 UTC, New Madrid, Missouri Magnitude ~7.0 – 7.8
1812, February 7, 09:45 UTC, New Madrid, Missouri Magnitude ~7.4 – 8.0
Large earthquakes in southeastern Canada, including:
The 1925 Charlevoix-Kamouraska earthquake (Magnitude 6.2);
The 1929 Grand Banks (or Laurentian Slope) earthquake (Magnitude 7.2) which generated a 7 meter tsunami in Newfoundland;
The 1935 Timiskaming (or Témiscaming) earthquake (Magnitude 6.2);
The 1944 Cornwall-Massena earthquake (Magnitude 5.6).
The 1988 Saguenay earthquake (Magnitude 5.9).
There are a number of named seismic zones along the western line of earthquakes. The most famous is the New Madrid seismic zone but the Charlevoix-Kamouraska zone in Quebec also generates a lot of earthquake activity. In fact all of the Canadian earthquakes listed above except for the Grand Banks event lie on the “line” of earthquakes that runs through Ohio. Between those two zones there are other lesser known zones in southern Illinois/Indiana, western Ohio near Anna, and northeastern Ohio near Painsville. But the activity seems to thin out through Ohio…is that because that region is just more stable or is it because the stresses are still accumulating in the faults here? There have been large historical earthquakes on both ends of “our line”. Ohio is in the middle. Could we have a large earthquake here in Ohio?
My amateur speculations are generally corroborated in the two page GeoFacts No.3 published by the Ohio Department of Natural Resources Division of Geological Survey. But my questions are not answered…the nature of Ohio’s subterranean faults is just not known.
Earthquakes are not something we live with on a daily basis in Ohio. Most people in Ohio don’t even think about earthquakes. I don’t expect a large earthquake here during my lifetime…but knowing what I know, however limited that knowledge is, I won’t be surprised if there is one.
A little more web browsing yielded a more complete description of Ohio seismicity and a listing of significant earthquakes in Ohio…. Earthquakes in Ohio by Michael C. Hansen. Interesting reading.
Also see my review of Seth Stein’s book “Disaster Deferred – How New Science is changing Our View of Earthquake Hazards in the Midwest”