Illinois, followed by Tennessee, have become the newest above 2.5 shakes to show on the USCS midwest system map. The Illinois earthquake epicenter is on the northern edge of the Wabash Valley Seismic Zone. Here are a few events from the past, though most are below today’s event it is located on a projected higher level event line.
This region is known as a liquefaction formation. Liquefaction sites and sand dikes show the evidence of past earthquakes in the region. Examining the size of the dikes and sediment found within the sand dikes, tests have estimated the size of the earthquake it took to create the formations. In the mid-1980’s a liquefaction formation was carbon dated to 6,100 years ago. The earthquake that produced the site was estimated to be a magnitude 7.1, large enough to seriously disrupt the area now known as the Wabash Valley Seismic Zone. in 1964 a 5.4 EQ was felt by 40,000 people over 16 states. June 18, 2002, a 5.0 magnitude earthquake struck 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. April 18, 2008, a 5.4 magnitude earthquake struck near Mt. Carmel, Illinois.
The Tennessee EQ is in a region that has been upgraded to a higher risk area. It is marked in red. This was added in 2008 and seems spot on, where this above 2.5 plus epicenter is centered.
This region of TN is noted as under the influence of the San Madrid Fault Complex. Given the active Tomographic Operations, in the search for the unseen subterranean energy deposits, it is not a great surprise that we are seeing this type of activity.
As always, the Oklahoma region shows its last hour- red, last day- orange, and last week- yellow; sized to event, and showing the ongoing EQ Swarm in that abused region.
otterwalks: 26th March 2015