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Stress and Slip Potential of Quaternary Faults and Possible Tectonic Features in the Central and Eastern U.S.

Description: 

There are more than 60 known or suspected Quaternary tectonic features in the central and eastern United States, ranging from well-studied seismic zones and faults to nebulous uplifts and liquefaction deposits. Crustal stress data in the region were sparse when this list was drafted 25 years ago, but the number of available focal mechanisms has since increased 15-fold. This project develops a site-specific stress model for each of these 60 features that quantifies the slip potential of local faults as a function of orientation, predicting sense of slip and rake. For the most enigmatic features, this tests whether the suspected faults and proposed motion are compatible with the modern stress field. This work documents the slip compatibility of normal faults in South Dakota and the Brockton-Froid zone (MT) and likely incompatibility of proposed faulting in the Champlain Lowlands (VT), New York Bight, Pembroke/Lindside/Stanley-Villa Heights (WV/VA), Wiggins Uplift (MS), and Monroe Uplift (LA). In many liquefaction and seismic zones, the causative faults have not been identified. Digitizing geologic maps and computing the slip potential of mapped faults illuminates candidate faults for the Moodus, CT swarm, 1727 Newburyport, MA liquefaction features, and 1886 Charleston earthquake, while several previously proposed faults are found to be poorly oriented. Short-wavelength stress variations in active areas influence fault activity and fault network connectivity. Transpression and clockwise stress rotation pervade the New Madrid (NMSZ) and Wabash Seismic Zones but do not impact immediately adjacent features (Ste. Genevieve, Cape Girardeau, Thebes Gap, West fault, western AR liquefaction). Moreover, dynamic rupture simulations suggest that second-order stress variations within the NMSZ may control rupture linkage vs. segmentation across the fault network and thus the occurrence of M7.5+ earthquakes.

Session: Earthquakes, Lithospheric Structure, and Dynamics in Stable Continental Region [Poster]

Type: Poster

Date: 4/17/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Will

Student Presenter: No

Invited Presentation: 

Poster Number: 64

Authors