Don’t move to Richmond or any delta or riverine areas in the lower mainland with sediment deposition. Read what happened in Japan. If the big one comes jiggle jiggle sink sink. water and soil becomes one. Mud.
The duration of the Japanese earthquake, about five minutes, could be the key to the severity of the liquefaction and may force researchers to reconsider the extent of liquefaction damage possible.
“With such a long-lasting earthquake, we saw how structures that might have been okay after 30 seconds just continued to sink and tilt as the shaking continued for several more minutes,” Ashford said. “And it was clear that younger sediments, and especially areas built on recently filled ground, are much more vulnerable.”
An event almost exactly like Japan’s is expected in the Pacific Northwest from the Cascadia Subduction Zone, and the new findings make it clear that liquefaction will be a critical issue in the young soils there.
“Young” sediments, in geologic terms, are those deposited within the past 10,000 years or so.
“Entire structures were tilted and sinking into the sediments, even while they remained intact,” said Ashford, who is based in Corvallis, Ore. “The shifts in soil destroyed water, sewer and gas pipelines, crippling the utilities and infrastructure these communities need to function. We saw some places that sank as much as 4 feet,” or 1.2 meters.