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Four major Holocene earthquakes on the Reelfoot fault recorded by sackungen in the New Madrid seismic zone, USA

February 11, 2019

Three sequences of well-documented, major ~M7+ earthquakes (1811-1812 CE, ~1450 CE, and ~900 CE) in the New Madrid seismic zone, USA, contribute significantly to seismic hazard in the region. However, it is unknown whether this <550 yr recurrence interval has been constant throughout the Holocene given limited geomorphic evidence of prior earthquakes. We extend the record of paleoearthquakes along the Reelfoot fault via investigation of ridge-top gravitational failure features, interpreted as sackungen. The sackungen occur in bluffs along the eastern margin of the Mississippi River floodplain and are concentrated near (<15 km) the southwest-dipping Reelfoot reverse fault. A paleoseismic trench excavated across sackungen at the Paw Paw site exposed four packages of colluvial sediment that postdate 30-11 ka Peoria loess. We interpret the colluvial packages to have been deposited following episodic failure of the sackungen as a result of strong ground motions from the following sequence of earthquakes: event 4, 1640 ± 1730 BCE; event 3, 340 ± 670 CE; event 2, 1430 ± 380 CE; and event 1, 1810 ± 50 CE (2-sigma). Event timing corresponds to previously documented earthquakes and represents the longest archive of paleoearthquakes on the Reelfoot fault. If the trenched sackungen record all major Reelfoot fault earthquakes, our observations in combination with prior investigations indicate a period of quiescence from at least 11 – 4.7 ka, followed by four major seismic events culminating in the 1811-1812 CE sequence. This clustered earthquake recurrence helps place bounds on seismic-hazard and geodynamic models in the New Madrid seismic zone.

Publication Year 2019
Title Four major Holocene earthquakes on the Reelfoot fault recorded by sackungen in the New Madrid seismic zone, USA
DOI 10.1029/2018JB016806
Authors Ryan D. Gold, Christopher DuRoss, Jaime E. Delano, Randall W. Jibson, Richard W. Briggs, Shannon A. Mahan, Robert Williams, D. Reide Corbett
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research B: Solid Earth
Index ID 70203031
Record Source USGS Publications Warehouse
USGS Organization Geologic Hazards Science Center