An Ancient Rift Complex and its relation to contemporary seismicity in the New Madrid Seismic Zone

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Abstract
Gravity, magnetic, geologic, and seismicity data have been combined in a seismotectonic analysis of the New Madrid seismic zone. Previous studies have presented evidence for several rift zones in this area (Upper Mississippi embayment), including the Reelfoot rift, a late Precambrian‐early Paleozoic failed arm which extends N‐NE from the ancient continental margin. In this study, we propose that the northern terminus of the Reelfoot rift forms a rift complex which appears to correlate well with the seismicity in the area. This correlation suggests that faults associated with this rift complex are being reactivated in the contemporary stress field (ENE compression). If this interpretation is valid, it represents a seismotectonic model which can be used to predict the extent of future seismicity in the New Madrid seismic zone. The proposed rift complex also provides a coherent model for the tectonic development of this region of the North American midcontinent.