GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 195-26
Presentation Time: 9:00 AM-6:30 PM


PETERSON, Alan E., Kansas Geological Survey, University of Kansas, 1930 Constant Ave, Lawrence, KS 66047-3726, SMITH, Jon J., Kansas Geological Survey, 1930 Constant Ave, Lawrence, KS 66047-3726, LAYZELL, Anthony L., Kansas Geological Survey, University of Kansas, 1930 Constant Ave, Lawrence, KS 66047 and LUDVIGSON, Greg A., Kansas Geological Survey, University of Kansas, 1930 Constant Avenue, Lawrence, KS 66047

South-central Kansas, like other parts of the central and eastern United States, resides in a region of relatively low historical and instrumentally recorded seismicity. Despite this, the state has experienced approximately 3,500 earthquakes since 2013, with more than 130 of the events recorded as magnitude 3.0 or greater. This recent spate of seismicity raises concerns about the potential risk that structural features (faults, folds, joints, and ridges) may pose for moderate to large earthquakes. Past movement along basement structural features may be visible as faults, lineaments, and structural features at the surface. Lineaments were mapped using aerial photography and bare-earth LiDAR Digital Elevation Models (DEMs), though the majority of these features are exclusively visible in hillshaded or otherwise post-processed LiDAR data. Although mapping lineaments may be a somewhat subjective endeavor, criteria were applied in an effort to standardize the threshold for what was mapped as a structural feature. These criteria are: (1) visible offset in marker beds; (2) relatively low- to high-relief linear ridges that are not obvious geomorphic features due to erosion, slumping, subsidence, or dune formation; (3) linear ridges that cross drainage divides; (4) ridges that display curvilinear and/or backstepping (en-echelon) configurations; (5) rectilinear or parallel drainage patterns; (6) linear drainage patterns that align across drainage divides. More than one criterion may have been met to map one feature. To date, more than 10,000 new features have been digitized. In many cases, mapped surface features overlie known basement structures and may be used to infer basement structures where they are not already known. Some fault trends exhibit an en echelon or anastomosing configuration. The spatial configuration of individual fault trends may be interpreted to understand the structural forces that generated the fault trend. Patterns revealed by mapping these surface features suggest a complex structural history.