“Is there any worse soil in Portland that we could have built on?” she asked.
Wang, an engineer with Oregon’s Department of Geology and Mineral Industries, known as DOGAMI, wrote a report in 2013 that said an earthquake could cause this ground to liquefy, as she had just now demonstrated.
“The risk here is extreme,” she said. After an earthquake, “within 10, 20 seconds, the sand will turn into a thick, sandy soup.”
And that would be bad.
Soil liquefaction, as it’s known to geologists, can exacerbate shaking and destroy roads, buildings and underground pipes. If that happens in Portland, it could devastate supply lines for fuel, electricity and natural gas. It also could mean a major chemical spill into the Willamette River.
What exactly is the problem?
Oregon’s petroleum reserves, along with substations, key pipelines and natural gas storage, are highly concentrated in one stretch along the Willamette River. Scientists now know that stretch of land poses a higher seismic risk than other parts of the city.
DOGAMI modeling for a magnitude-9 earthquake shows most of the petroleum tanks in that area sit on soils the agency considers to have a medium to high probability of liquefaction. The area also is predicted to have very strong shaking.
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