Detecting the unseen
A team of ҽresearchers use satellite radar imagery to reveal hundreds of unseen landslides occurring in Western U.S. states.
ҽgeophysicists have used satellite imagery to identify more than 600 slow-moving landslides occurring near the U.S. West Coast.
Fewer than 5% of these landslides in California, Oregon and Washington state had previously been identified.
Geophysics professor Zhong Lu and his team at ҽwere awarded nearly $1 million over the past four years from the NASA Interdisciplinary Research in Earth Science Program and the NASA Earth Surface and Interior Focus Area to study landslides on the West Coast.
Most of the large landslides they found were in the mountain ranges of western Washington, southwestern Oregon and northwestern California. In some cases, the identified landslides were within 0.5 to 5 kilometers of multiple towns and roads.
“These landslides are currently moving slowly. But they’re already in a state of force imbalance. So some other external forces, like earthquakes or rainfall, could shift them into a disaster,” says Yuankun Xu, a postdoctoral researcher who works in Lu’s ҽRadar Laboratory and lead author of a study published in the journal Landslides.
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Co-author Lu, Shuler-Foscue Chair at SMU’s Roy M. Huffington Department of Earth Sciences, says, “We don’t want to give the impression that these landslides are in trouble tomorrow. No, these landslides have a life expectancy ranging from years to a thousand years.”
Still, the researchers urged policymakers in these Western states to monitor the movement of the now-identified landslides so they can prevent a catastrophe from happening.
“I would be very concerned if living, working or commuting upon or near any of the landslides,” says study co-author William H. Schulz, a research geologist in the USGS’ Landslide Hazards Program. “However, humans can and have successfully dealt with individual landslides and potentially unstable slopes in the past. Detailed studies performed by professionals involving engineering geologic characterization and modeling are needed for any landslide to accurately estimate and mitigate potential future hazards.”
Landslides kill thousands of people every year worldwide
Landslides occur when masses of rock, soil or earth fall down a slope because of gravity. They cause thousands of deaths each year around the world, and in the United States alone, damage exceeds $2 billion annually from these slides.
Xu, Lu and the rest of the research team used radar satellite images to unravel previously unidentified landslides from space.
With interferometric synthetic aperture radar technology (called