Liquefaction Potential of Sediment in the Northern Bering Sea

The liquefaction potential of sediment in Norton Sound and the northern Bering Sea was evaluated by estimating the liquefaction susceptibility of the material from in-situ and laboratory tests in terms of earthquake and wave loads required to liquefy the material, and then comparing estimated behavior with anticipated loadings caused by frequent storm waves in the relatively shallow water depths and infrequent earthquakes.

In-situ cone penetration tests (CPT) were performed at 13 stations. After the CPT data were transformed into equivalent standard penetration test (SPT) blow counts, analyses were performed that determined earthquake accelerations and sustained relative storm wave heights that would cause liquefaction.

Vibratory core samples, up to 6 m long, were obtained in silty sand grading to sandy silt near many of the CPT locations. Results of cyclic triaxial tests performed on those samples were used to calculate earthquake accelerations and sustained storm wave heights that would liquefy the sediment.

Liquefaction susceptibility estimates from laboratory tests typically were lower than those from in-situ tests; nevertheless, both approaches yielded the same conclusions for regional assessment of liquefaction potential. Wave and earthquake loadings are not strong enough to cause significant amounts of liquefaction in most areas.