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Late Holocene deformation near the southern limits of the Wabash Valley seismic zone of Kentucky and Indiana, central United States, with seismic implications

Ronald C. Counts, Roy Van Arsdale, Edward Woolery, Madhav K. Murari, Lewis A. Owen, E. Glynn Beck, Shannon Mahan and James Durbin
Late Holocene deformation near the southern limits of the Wabash Valley seismic zone of Kentucky and Indiana, central United States, with seismic implications
Bulletin of the Seismological Society of America (June 2021) 111 (2): 1154-1179

Abstract

The Wabash Valley seismic zone (WVSZ) is a region of diffuse, modern intraplate seismicity in the central United States with a history of strong, late Quaternary and Holocene seismicity as determined through paleoliquefaction studies. Yet, there are no specific faults linked to these strong WVSZ paleoearthquakes, some of which were as large as Mw 7.2-7.5. A multidisciplinary investigation of a linear, 5-kilometer-long and approximately 3-meter-high scarp on the Ohio River floodplain in the southernmost WVSZ in western Kentucky evaluated whether the scarp is a fluvial landform or a tectonic feature. Geomorphic mapping and optically stimulated luminescence geochronology show that the age and orientation of the scarp are inconsistent with surrounding fluvial landforms. Trenching, core drilling, seismic reflection, electrical resistivity profiling, and cross sections of petroleum well logs all indicate a blind fault directly underlies the scarp. The scarp is interpreted to be the fold axis of a down-to-the-west monocline formed in alluvium by slip on the underlying blind fault, herein named the Uniontown fault. The Uniontown fault connects the Hovey Lake fault, striking N20 degrees E and having approximately 0.5 km of documented strike-slip offset, with an unnamed fault complex to the south that strikes N40 degrees E, suggesting the Uniontown fault is part of a larger, Paleozoic structure that has been reactivated with strike-slip deformation. Geomorphic mapping utilizing luminescence and radiocarbon geochronology indicates that folding and faulting occurred approximately 3.5 ka. Paleoliquefaction was suppressed by a thick clay cap in the main Ohio Valley, but paleoliquefaction features are widespread on Ohio River tributaries. Gravel dikes at one site had a maximum age of 3.4+ or -0.4 ka, confirming the region has experienced strong, late Holocene shaking. Estimates using vertical displacement and rupture length indicate that slip on the Uniontown scarp could produce an Mw 6.2-7.7 earthquake, which is comparable to other large paleoearthquakes in the WVSZ paleoseismic record.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 111
Serial Issue: 2
Title: Late Holocene deformation near the southern limits of the Wabash Valley seismic zone of Kentucky and Indiana, central United States, with seismic implications
Affiliation: University of Mississippi, Department of Geology and Geological Engineering, Oxford, MS, United States
Pages: 1154-1179
Published: 202106
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 138
Accession Number: 2021-043784
Categories: SeismologyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch maps
N37°00'00" - N39°00'00", W89°00'00" - W87°00'00"
Secondary Affiliation: University of Memphis, USA, United StatesUniversity of Kentucky, USA, United StatesInter-University Accelerator Center, IND, IndiaNorth Carolina State University, USA, United StatesKentucky Geological Survey, USA, United StatesU. S. Geological Survey, USA, United StatesUniversity of Southern Indiana, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2021, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202114
Program Name: USGSOPNon-USGS publications with USGS authors
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