| 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. |
| Genre: | Article |
| ProdID: | 70042523 |
| Citation Author: | Thomas L Pratt |
| Citation Contributing Office: | Earthquake Science Center |
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| Citation End Page: | 374 |
| Citation Issue: | 4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geology |
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| Citation Month: | 2 |
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| Citation Publisher: | Geological Society of America |
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| Citation Search Results Text: | Kinematics of the New Madrid seismic zone, central United States, based on stepover models; 2012; Article; Journal; Geology; Thomas L Pratt |
| Citation Start Page: | 371 |
| Citation Volume: | 40 |
| Citation Year: | 2012 |
| Type: | citation/reference |
| Text: | Kinematics of the New Madrid seismic zone, central United States, based on stepover models; 2012; Article; Journal; Geology; Thomas L Pratt |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1130/G32624.1 |
| Date Other: | Thu, 1 Mar 2012 00:00 -0600 |
| Publisher: | Geological Society of America |
