AUSTIN (KXAN) — Landslides cause more than a billion dollars in damage in the United States each year, according to the American Geoscience Institute. Predicting them could soon be a lot easier.
“We’ve all seen on the news probably the mudflows that just let loose and take out small towns or neighborhoods or houses,” said Deman Saffer, director of the Institute of Geophysics at the University of Texas.
At a recent science conference, Saffer witnessed a speech on slow landslides. He realized his research on slow earthquakes could benefit the University of California at Santa Cruz researchers.
“An earthquake versus a slow earthquake is very analogous to a catastrophic landslide that fails very quickly versus a creeping landslide,” Saffer said.
The researchers partnered up and, in a new research paper, were able to unlock some of the secrets of the two damaging Earth events. “They’re very similar, smaller scale, shallower depths, but the physics are the physics,” Saffer said.
With this study, we’re now closer than ever to predicting earthquakes and landslides before they happen.
Hard rock and the creeping Earth
It all comes down to rocks. The team found that if landscapes are soft and clay-like, slow-creeping landslides and slow earthquakes are more likely.
During a slow earthquake, tectonic plates move against each other over a long stretch of time. This releases energy over a longer period, and in turn, causes less damage.
During a slow landslide, mud and dirt creep downhill. Foundations pull apart over time, trees slowly shift and roads can crack. A slow landslide is devastating but doesn’t come with the massive loss of life.
When rock is hard, however, we get that devastation. Energy builds up over time as tectonic plates and rocks crunch against each other. Big earthquakes. Life-shattering landslides.
Saffer said the big question is simple: “If you do have these creeping landslides, what controls how fast they creep and what’s going to happen?”
Water beneath the surface likely plays a role.
“If you have a higher water pressure, it’s almost like lifting the landslide up a little bit in the same way that it would like Jack open a fault a little bit. So it’s not being clamped together as hard, and that allows it to move more readily,” Saffer said.
This happens to landslides and earthquakes. Think about it: rain can bring about landslides. Storms are not only loosening the dirt but lifting it from the rock below.
Understanding these similarities doesn’t just help landslides, but earthquake researchers as well. “If the physics are kind of similar or analogous, landslides are much more accessible. We don’t have to go to the bottom of an Ocean Trench,” Saffer said.
