Analysis of the Seismic Origin of a Landslide in the New Madrid Seismic Zone

Abstract

Abstract The New Madrid earthquakes of 1811–12 reportedly triggered many landslides from the bluffs east of the Mississippi River. We use static and dynamic slope stability analyses to determine if landslides currently visible in this area were triggered by seismic shaking or if failure could have occurred in aseismic conditions. We apply this approach to a translational block slide representative of a group of old landslides that previous investigations showed probably were triggered in 1811–12. Slope-stability modeling of aseismic conditions shows that the slide could not have formed aseismically even in unrealistically high ground-water conditions. Dynamic stability analysis using Newmark’s method shows that the landslide would have experienced large displacements – sufficient to cause catastrophic failure – during earthquake shaking similar to that which occurred in 1811–12.