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PSU research: Microbe gas could ‘cushion’ buildings during quakes

Oregonians could rely on some of the smallest organisms to survive a big earthquake.

Researchers at Portland State University are looking at how microbes could strengthen soil in the event of an earthquake.

Diane Moug, an assistant professor at PSU, says even smaller quakes than the potential magnitude 9.0 Cascadia Subduction Zone earthquake could cause liquefaction — meaning soil is so saturated with water that it essentially acts like liquid as it shakes.

Moug describes the process of “microbial-induced desaturation,” in which microorganisms feed on nutrients and secrete small bubbles of gas.

“If the ground shakes from the earthquake, these bubbles – they’re cushioning the ground, they’re lessening that impact of the shaking, and they’re strengthening the ground so that we don’t get the strength loss that you would expect without those bubbles present,” she explains.

Moug notes two areas in Portland at risk of liquefaction are major concerns for the state.

First is the airport, which could leave the city and surrounding area without a lifeline following an earthquake.

Second is the Critical Energy Infrastructure Hub, where tanks hold 90% of the state’s liquid fuel supply.

Moug says she and the other PSU researchers are conducting the largest-scale trial of this method. She notes if it’s effective, it could significantly reduce the cost of securing buildings against liquefiable soil.

Currently, soil is boosted with injections of cement from the sides of a building, or using stone columns to support the building – usually installed during construction.

Moug says it would take less effort as well.

“It’s not as invasive because we’re just reusing what’s already in the ground,” she states. “We’re just adding a little bit to stimulate things.

“So, it could be done for existing structures with a fairly low impact to the structure and the surrounding ground of the structure.”

Moug says the National Science Foundation developed and has been driving this research forward in collaboration with Arizona State University.

KTVZ 2019

Article Topic Follows: Earthquake

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