West Coast Earthquake Preparedness - The Big One is Overdue
"During an earthquake loose water-saturated silts and sands at shallow depth may lose their strength and transform into a fluid (liquefaction). Deeper sediments are more consolidated, have higher confining pressures, and consequently are less likely to liquefy. When sand beneath a layer of silt or clay liquefies, the capping layer may "glide" laterally under the influence of gravity towards a slope, such as the bank of a nearby river channel, causing ground cracking. Foundations of highways, bridges, and buildings, as well as buried sewer and gas lines, can be damaged by such movements. Liquefaction can also trigger landslides at the front of the Fraser delta. " Source
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