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Kinematics of the New Madrid seismic zone, central United States, based on stepover models

Geology

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DOI: 10.1130/G32624.1

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Abstract

Seismicity in the New Madrid seismic zone (NMSZ) of the central United States is generally attributed to a stepover structure in which the Reelfoot thrust fault transfers slip between parallel strike-slip faults. However, some arms of the seismic zone do not fit this simple model. Comparison of the NMSZ with an analog sandbox model of a restraining stepover structure explains all of the arms of seismicity as only part of the extensive pattern of faults that characterizes stepover structures. Computer models show that the stepover structure may form because differences in the trends of lower crustal shearing and inherited upper crustal faults make a step between en echelon fault segments the easiest path for slip in the upper crust. The models predict that the modern seismicity occurs only on a subset of the faults in the New Madrid stepover structure, that only the southern part of the stepover structure ruptured in the A.D. 1811–1812 earthquakes, and that the stepover formed because the trends of older faults are not the same as the current direction of shearing.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Kinematics of the New Madrid seismic zone, central United States, based on stepover models
Series title:
Geology
DOI:
10.1130/G32624.1
Volume
40
Issue:
4
Year Published:
2012
Language:
English
Publisher:
Geological Society of America
Contributing office(s):
Earthquake Science Center
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
371
Last page:
374
Country:
United States