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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 101, NO. B3, PAGES 6151–6170, 1996

Multiple late Holocene earthquakes along the Reelfoot fault, central New Madrid seismic zone

Keith I. Kelson

William Lettis & Associates, Walnut Creek, California


Gary D. Simpson

William Lettis & Associates, Walnut Creek, California


Roy B. VanArsdale

Department of Geological Sciences, University of Memphis, Memphis, Tennessee


Colleen C. Haraden

William Lettis & Associates, Walnut Creek, California


William R. Lettis

William Lettis & Associates, Walnut Creek, California


Abstract

The Reelfoot fault is an east vergent, reverse fault underlying the Lake County uplift, a low-amplitude, late Holocene anticline bordered on the east by the 32-km-long Reelfoot scarp. Fluvial deposits across the scarp define an 8-m-high, east facing monocline. Most near-surface deformation along the scarp is accommodated via folding rather than faulting. We interpret the scarp as a fault-propagation fold developed over a west dipping reverse fault interpreted from shallow seismic reflection data. Trench exposures provide evidence for three episodes of deformation along the Reelfoot fault within the past approximately 2400 years, between A.D. 780 and 1000, between A.D. 1260 and 1650, and during A.D. 1812. Our best estimate of the average recurrence interval for deformation along the scarp is 400–500 years. Each episode of deformation had a slightly different style. The third most recent event produced a small graben a few tens of centimeters deep in the hanging wall of the reverse fault. The second most recent earthquake produced about 1.3 m of throw in the graben, as well as folding along the updip projection of the reverse fault and development of the scarp. These relations suggest that graben development increased through time concomitant with growth of the monocline or that the events are of different magnitude. The 1811–1812 episode of deformation produced abundant liquefaction, prominent folding of fluvial strata along the scarp, and minor faulting in the graben.

Received 30 September 1994; accepted 13 June 1995.

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Citation: Kelson, K. I., G. D. Simpson, R. B. VanArsdale, C. C. Haraden, and W. R. Lettis (1996), Multiple late Holocene earthquakes along the Reelfoot fault, central New Madrid seismic zone, J. Geophys. Res., 101(B3), 6151–6170.