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News Release, Kansas Geological Survey, Aug. 17, 2001

KGS Seismic Crew to Study Subsidence in Eastern Reno County

LAWRENCE--An area that is slowly sinking along U.S. Highway 50 east of Hutchinson will be the subject of study by researchers from the Kansas Geological Survey, based at the University of Kansas.

The researchers will use shallow seismic reflection techniques to study the sinking, or subsidence, near the intersection of Victory Road and U.S. 50, about six miles east of Hutchinson, beginning August 21.

Survey scientists will use techniques similar to those they employed last winter west of Hutchinson in the search for pathways that natural gas used to move beneath the city.

The work along U.S. 50, however, is unrelated to last winter's natural gas incident. This time scientists will be looking for the cause of subsidence in the roadbed. That subsidence amounts to a few feet since it was first noticed in 1998 and is probably related to the layer of salt that underlies the area, the same salt layer that is mined in Hutchinson. East of the city, the salt bed is only about 400 feet underground and ends west of the Reno County/Harvey County line.

At the edge of the salt layer, where the salt is close to the surface, the likelihood increases that fresh water will reach the salt and dissolve it away, creating open space that then slowly settles, creating subsidence at the surface. The area where this occurs is known geologically as a "solution front," and is marked by a number of sinkholes that then fill with water.

The Survey's seismic reflection study along U.S. 50 is being done in cooperation with the Kansas Department of Transportation. KDOT wants more information about the underground geology to determine the best approach for fixing the roadbed.

Seismic reflection is a technique in which vibrations are set off at the surface (in this case, with a specially designed truck), then recorded as they echo off of underground rock layers. The results can be used to create an image of the underground geology.

The Survey seismic crew expects to complete the data collection by August 25. That information will be processed and analyzed before being submitted to KDOT this fall.

Story by Rex Buchanan, (785) 864-2106

Kansas Geological Survey, Publications and Public Affairs