Necessary Conditions for Intraplate Seismic Zones in North America. Issue 12 (11th December 2017)

• Record Type: Journal Article
• Authors: Thomas, William A.; Powell, Christine A.
• Is Part Of: Tectonics. Volume 36:Issue 12(2017)
• Page Start: 2903
• Page End: 2917
• Publication Date: 2017-12-11
• Subjects: seismicity -- intraplate -- seismotectonics; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1002/2017TC004502
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: The cause of intraplate seismic zones persists as an important scientific and societal question. Most intraplate earthquakes are concentrated in specific seismic zones along or adjacent to large‐scale basement structures (e.g., rifts or sutures at ancient plate boundaries) within continental crust. The major intraplate seismic zones are limited to specific segments and are not distributed along the lengths of the ancient structures. We present a new hypothesis that major intraplate seismic zones are restricted to places where concentrated crustal deformation (CCD) is overprinted on large‐scale basement structures. Examples where CCD affects the stability of specific parts of large‐scale structures in response to present‐day stress conditions include the most active seismic zones in central and eastern North America: Charlevoix, Eastern Tennessee, and New Madrid. Our hypothesis has important implications for the assessment of seismic hazards. Plain Language Summary: The cause of seismic zones far from tectonic plate boundaries persists as an important scientific and societal question. Most of the intraplate seismic zones are concentrated along or adjacent to large‐scale, ancient basement structures within continental basement crust. The major seismic zones are limited to specific segments and are not distributed along the lengths of the ancient structures. We present a new hypothesis that major seismic zones are restricted to places where the large‐scale basement structures have been damaged by concentrated crustal deformation. Examples where the additional deformation affects the stability of specific parts of large‐scale structures in response to present‐day stress conditions include the most active seismic zones in central and eastern North America: Charlevoix, Eastern Tennessee, and New Madrid. Our hypothesis has important implications for the assessment of seismic hazards. Key Points: Intracratonic seismic zones are located where concentrated crustal deformation overprints basement structure The presence of concentrated crustal deformation will lower the vertically integrated strength of the crust, facilitating seismic activity Future seismic zones may occur where concentrated crustal deformation overprints basement structure