INVESTIGATION OF CRUSTAL STRUCTURE IN THE NEW MADRID SEISMIC ZONE USING INDUSTRY REFLECTION DATA

BROWNING, S.,LANGSTON,C., and VAN ARSDALE, R., Center for Earthquake Research and Information, Univeristy of Memphis, Memphis,TN 38152, Department of Earth Sciences, University of Memphis, Memphis,TN 38152, sbrownng@memphis.edu,

clangstn@memphis.edu, rvanrsdl@memphis.edu.

The New Madrid seismic zone (NMSZ), located in the central United States, is the most seismically active zone east of the Rocky Mountains. It lies within the Reelfoot rift, a northeast-trending basement fault zone. Historical records and paleoseismic research indicate this region has experienced at least three major prehistoric events that occurred in approximately A.D. 1450,A.D. 900,and A.D. 490, in addition to the three large earthquakes estimated at M 7.8 to 8.1 in the winter of 1811-1812. A thorough understanding of the underlying structures and processes responsible for seismicity has not been determined. Recent studies suggest significant seismicity does not extend beyond a proposed eastern margin of the rift, leading to conjecture that the margin is accumulating strain, posing unknown seismic hazards for the central U.S. Seventeen seismic reflection lines are located adjacent to this margin and are being reprocessed to delineate crustal structure and provide information on fault geometry. Geologic interpretation of resulting structures will be constrained by available magnetic and gravity data, further defining the structure of the eastern margin and providing insight into seismic hazards for the central and eastern U.S.