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Time-Lapse High Resolution Seismic Imaging of A Catastrophic Salt Dissolution Sinkhole In Central Kansas
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 18th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems, Apr 2005, cp-183-00115
Abstract
Time-lapse 2-D high-resolution seismic reflection surveys successfully imaged and mapped<br>changes in structural features associated with a sinkhole that formed catastrophically after dissolution of<br>the Permian-age Hutchinson Salt in central Kansas (Figure 1). Symmetric steep sided cone structure<br>defined by reverse faults formed instantaneously continuing over time to gradually enlarge and elongate<br>along normal fault planes. Two orthogonal high-resolution seismic lines were acquired, in 1998 and<br>2004, to map the upper thousand feet and resolve structural features controlling development subsidence<br>rate preferential dissolution mechanism for fluid movement and to predict future growth. High<br>frequency vibrator and high-resolution seismic methods were used to acquire data from a 204 channel<br>fixed spread. Stations used in 1998 were as close as possible reoccupied on the 2004 survey. Common<br>mid-point stacked sections depict a very disturbed subsurface that has undergone multiple discrete<br>phases of loading, failure, and subsidence. Stress built up in roof rock overlying the salt void until its<br>strength is surpassed when failure, and subsidence occurs (Figure 2 (a), (b), and (c)). Strain associated<br>with layers bridging voids outside the tensional dome appears to be controlled by normal faults. Oilfield<br>disposal practices provided original fluids and pathway that initiated the dissolution process.<br>Currently shallower groundwater fuels the dissolution process with little or no contribution from<br>oil-field brines. Growth appears to be controlled by geologic trends with failure occurring much more<br>plastically during the later years, which initially growth was characterized by rapid brittle<br>deformation.