Identification of liquefaction and deformation features using ground penetrating radar in the New Madrid seismic zone, USA

Ground penetrating radar (GPR) surveys were conducted in the New Madrid seismic zone in the central US. The targets of the GPR surveys were the near-surface sedimentary features associated with seismically induced liquefaction and stratigraphic disturbances. Correlation of the features shown by the GPR data and "ground truth" revealed by geological excavation holds the promise of using GPR to assist optimal selection of future trenching sites. The present paper reports GPR survey results using a 400 MHz antenna at the site of Haynes Farm in Arkansas for paleoliquefaction studies; and using 400 and 100 MHz antennas at three sites along the western scarp of the Sikeston Ridge in Missouri for near-surface deformation studies. The 400 MHz data at the paleoliquefaction site in Haynes Farm characterized an elongated sand blow feature at a depth of about I in, with an almost east-west striking orientation. At the Sikeston Ridge site, GPR surveys were carried out at one excavation site near Davis Cemetery in the village of Kewanee, Missouri, using the 400 MHz antenna. Another three GPR profiles with lengths of more than 100 in and crossing the western scarp of the Sikeston Ridge were collected using the 100 MHz antenna. Since the soils in this area are rather sandy, the 100 MHz antenna produced the best data and penetrated to depths of 6-7 in. The GPR surveys reveal similar subsurface deformation features at depth for all three 100 MHz profiles. Correlating GPR profiles with trenching, drilling, and satellite imaging confirms that the stratigraphic disturbances shown at shallow depths are associated with erosional trimming, colluvial deposition, and channel incision of the west margin of the Sikeston Ridge, occurring in the latest Wisconsin time about 10000 years BP. The examples show that GPR is useful in locating subsurface features in the New Madrid seismic zone for seismic hazard assessments. (C) 2001 Elsevier Science B.V. All rights reserved.