34-4 "Geomorphic Evidence of Neotectonic Activity in the Wabash Valley Seismic Zone: Insights from LiDAR-Derived Swath Profile Analysis"

Session: Advancing Earthquake Geology and Surficial Deformation from Geologic Provinces to Political Entities through Multidisciplinary High-Resolution Data (Posters)

Presenting Author:

Authors:

Abstract:

The Wabash Valley Seismic Zone (WVSZ), located within the southern Illinois Basin of Indiana, Illinois, and Kentucky, is a significant intraplate seismic region with a documented history of strong Pleistocene earthquakes (Mw 6.0–7.5). While numerous subsurface faults have been identified with geophysical surveys and petroleum exploration, most remain buried beneath thick alluvium and loess deposits, making it difficult to conduct paleoseimic research in this region. This lack of surface expression, coupled with complex subsurface fault geometry and poorly constrained recurrence intervals, underscores the need for additional techniques such as geomorphic analyses to evaluate neotectonic activity.

To assess potential ground deformation related to tectonic processes, we constructed cross-valley topographic swath profiles using a high-resolution (3-ft) LiDAR-derived Digital Elevation Model (DEM). Eighteen swath profiles, each 2 km wide, were generated across the Wabash River Valley to capture elevation trends spanning the river channel, valley margins, and adjacent uplands. The study area was subdivided into upper, middle, and lower reaches, with six profiles analyzed per segment. Swath data—including minimum, maximum, and mean elevations as well as standard deviation—were plotted using interactive MATLAB scripts.

The analyses reveal distinct tilting patterns along the valley floor. In the upper reaches of the valley, alternating eastward and westward tilting corresponds with frequent river channel migrations. The middle reach exhibits persistent westward tilting, contributing to sustained westward channel migration and increased north-south meandering. In contrast, the lower reach displays relatively stable elevations, with subtle eastward tilting in its southernmost section, influencing eastward channel migration. These systematic tilting patterns suggest there is ongoing or recent deformation, likely associated with reactivation of buried faults, within the WVSZ.

Keywords: Swath profiles, Neotectonics, Tilting, Deformation

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11033

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