Identifying lateral spread fissures with ground penetrating radar in the New Madrid seismic zone

Ground penetrating radar (GPR) surveys have been conducted to identify the size, shape and orientation of relict lateral spread fissures created during the New Madrid earthquakes of 1811 and 1812. Aerial imagery was used to locate regions with elongate vented sand indicative of large-scale fissures. Five GPR surveys were conducted over these areas and correlated to two trenches and one hand-dug pit. Panda cone penetration tests (Panda CPT) were performed at three sites and correlated to the GPR data. 3D GPR models were created for each GPR survey, and grain size analyses were performed for sediment samples taken from both trenches and the pit. Correlation of the GPR data and the trenches indicate the GPR surveys accurately identified the sizes, orientations and locations of the fissures. The Panda CPT soundings correlated closely with the GPR data indicating that they could correctly identify sand intrusions and lithological changes in the subsurface. Interpolations of the GPR data for the two sites with trenches generated 3D volumes that correlated closely with zones of oxidation that were visible within the sand units viewed in the trenches. It is speculated that the 3D volumes generated for the remaining sites also correlate with zones of oxidation or light cementation within the sand units