Date

5-1-2020

Document Type

Thesis

Degree

Master of Science

Department

Earth and Environmental Sciences

First Adviser

Frank J. Pazzaglia

Abstract

Knickpoint elevations potentially record geomorphic signals of seismicity in

slowly deforming plate interiors that lack surface expressions of underlying seismic

faults. The presence or lack of cumulative differential uplift in knickpoint elevations may

shed light on the mechanisms driving intraplate seismicity, namely whether there is

dynamic plate-tectonic activity deep in the interior or whether seismicity is driven by

topography focusing stress on favored structures. The Reading-Lancaster Seismic Zone

(RLSZ) is one of several clusters of seismicity in the Appalachian Piedmont. Modeled

knickpoint ages derived from channel response times to impulsive base level falls

indicate that Pleistocene-age knickpoints in Susquehanna tributary streams have

undergone up to 10 m/Myr of differential uplift. Regional patterns of modeled

deformation are coincident with the E-W trending Westminster and Tucquan anticlines

and inconsistent with N-S trending faults. This study concludes that seismicity is driven

by the growth of the Westminster anticline releasing strain on preexisting faults.

Available for download on Friday, February 26, 2021

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