The influence of sedimentary architecture on the formation of earthquake-induced liquefaction features: A case study in the New Madrid seismic zone

Abstract

This study is aimed at understanding how the arrangement of fluvial sedimentary deposits and their physical properties influences the formation and location of liquefaction features resulting from earthquake strong ground motions. The study site is located in the Mississippi River floodplain in the New Madrid seismic zone of the central United States, an area that hosts abundant liquefaction deposits resulting from both historic and prehistoric earthquake sequences. We combine satellite imagery, electrical resistivity tomography, soil textural analyses and ditch exposures of liquefaction features to develop a model of how the spatial distribution of sedimentary deposits, such as point bars, overbank, levee, backswamp and channel-fill, contribute to pore pressure build-up and subsequent development of liquefaction features, such as sand dikes and sand blows, as water and entrained sediment forcefully flow toward the surface. The model helps to explain (1) the abundance of earthquake-induced liquefaction features present in the Mississippi River valley, where fine- to medium-grained saturated sands are interbedded with or overlain by fine-grained portions of channel-fill, levee, overbank or backswamp deposits, and (2) the concentration of liquefaction features along the margins of abandoned-channel fill, point bar and overbank deposits, as seen in other locations worldwide. This understanding can contribute to identifying areas where liquefaction may be a threat to engineered structures and limiting the extent of areas in which detailed engineering geology measurements (e.g., in situ testing) may be necessary.