Recent
studies have indicated that the New Madrid Seismic Zone
is not the only 'hot spot' for earthquakes in the Central
United States. On June 18, 2002, a 5.0 magnitude
earthquake struck the Evansville, Indiana with an epicenter
between Mt. Vernon and West Franklin in Posey County, in
an area that is part of the Wabash Valley Seismic Zone. According
to the Indiana University Indiana Geological Survey, while
there was minor damage associated with the earthquake,
the tremor was a warning to residents of the Wabash Valley
Seismic Zone that earthquakes can, and do, strike close
to home.
The Wabash
Valley Seismic Zone is located in Southeastern Illinois
and Southwestern Indiana and it is capable of
producing 'New Madrid' size earthquake events. Since
the discovery of this seismic zone, earthquake awareness
and preparedness have increased. Residents are seeing
that moderate sized earthquakes are not just occuring to
south, but occur right at home and can affect Illinois,
Indiana, and Kentucky.
Geologists
in Indiana and Illinois have found liquefaction sites and
sand dikes that shows the evidence of prehistoric earthquakes
in the region. By examining the size of the dikes and sediment
found within the sand dikes, geologists are able to estimate
the size of the earthquake it took to create the formations.
In the mid-1980’s, geologist Steven Obermeier found
a liquefaction formation that was estimated, through carbon
dating, to be 6,100 years old. The earthquake that produced
the site was estimated to be a magnitude 7.0, large enough
to seriously disrupt the area known as the Wabash Valley
Seismic Zone.
Current
research is still turning out new evidence of historic
earthquakes in the zone. For further informaiton,
browse through the links to the right. |