Accession Number : ADA337348

Title :   Seismic Hazards of the Upper Mississippi Embayment

Descriptive Note : Final rept

Corporate Author : MEMPHIS UNIV TN

Personal Author(s) : Van Arsdale, Roy

PDF Url : ADA337348

Report Date : JAN 1998

Pagination or Media Count : 132

Abstract : Earthquakes are a major hazard in the middle Mississippi River valley of the upper Mississippi embayment. Microseismicity along the New Madrid seismic zone is illuminating faults that are believed responsible for the great New Madrid earthquakes of 1811-1812. These faults are right lateral strike slip faults within the Blytheville arch and western margin of the Reelfoot rift that are linked by the southwest dipping Reelfoot reverse fault. The Bootheel lineament and back thrusts of the Reelfoot fault may also have slipped in 1811-12. Geomorphic effects of the 1811-12 sequence include displacement of the Mississippi River; uplift of the Lake County uplift, Tiptonville dome, Blytheville arch; subsidence of Reelfoot Lake, Big Lake, and Lake St Francis; landslides on the eastern bluffs of the Mississippi River valley; and extensive liquefaction. In addition there is evidence for 1811-12 landsliding on the eastern margin of Crowley's Ridge, formation of a lake on the Obion River, and formation of seismic craters on the loess covered eastern Mississippi Valley bluffs. Peripheral to the New Madrid seismic zone; the Big Creek, Commerce, and Crittenden County faults have Holocene displacement and faults along the margins of Crowley's Ridge have Pleistocene displacement. The margins of Sikeston Ridge are underlain by faults that apparently lifted the ridge in Quaternary time. Similarly, the eastern Mississippi Valley bluffs are underlain by faults that appear to have affected the current position of the Mississippi River. Thus, there is evidence for widespread Quaternary faulting within the upper Mississippi embayment Paleoliquefaction and trench excavations across the Reelfoot fault reveal a minimum of 3 prehistoric earthquakes and an estimated recurrence interval of 450 years.

Descriptors :   *EARTHQUAKES, *TECTONICS, HAZARDS, GROUND MOTION, FAULTS(GEOLOGY), SEISMIC WAVES, GEOMORPHOLOGY, MISSISSIPPI RIVER.

Subject Categories : Seismology

Distribution Statement : APPROVED FOR PUBLIC RELEASE