Centrifuge Study of Seismic Response of Submarine Clay Canyons-Paper

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The study used 40g centrifuge tests to investigate how submarine clay canyons affect seismic ground motions. Kaolin clay models included a flat surface and canyon slopes of 15°, 30° and 45°, representing features of Brazil’s southeastern continental margin. Researchers applied seismic motions of varying amplitudes and monitored accelerations, pore pressures, settlement and soil properties.<br /><br />The tests showed that even relatively low-intensity shaking could produce substantial amplification, particularly when the input frequency interacted with the soil deposit’s natural frequency. Seismic loading also reduced shear-wave velocity, indicating soil stiffness degradation; the effect was greater near the surface, where motion was more strongly amplified. Excess pore pressures were small and dissipated between shaking events.<br /><br />Amplification depended on both canyon geometry and input strength. The detailed comparisons generally found soil-layer effects to dominate the total response, while isolated topographic effects varied with slope angle and shaking amplitude. A steep slope produced notable topographic amplification under the weakest input, whereas stronger shaking tended to attenuate motions. The authors attribute these patterns partly to nonlinear soil behavior, which changes damping and shifts the soil and topographic frequencies.<br /><br />The findings indicate that canyon topography and nonlinear soil response should be considered when assessing seismic hazards to subsea infrastructure. Further testing is needed to clarify how these factors interact.

Keywords

submarine clay canyons

seismic ground motions

centrifuge tests

kaolin clay

topographic amplification

soil nonlinearity

shear-wave velocity

pore pressure

seismic hazards

subsea infrastructure