Why Do Landslides Flow Like a River?

Rivers are characterized by flowing water which is a characteristic observed in landslides. Now, scientists have figured out why a landslide can flow like a river using a computer model.

Landslides can travel longer distances than the usual water flow, often flowing like rivers and rushing over hills, Science Mag shared. A landslide mostly travels twice the distance of their fall. However, sturzstroms (long-runout landslides) can travel 10 to 20 times the distance, according to Brown University Assistant Professor and Journal of Geophysical Research Earth Surface Lead Author Brandon Johnson.

After developing several hypotheses, modern technology finally pointed the cause of river-like behavior of landslides to vibrations. Johnson resurrected the model used in past studies, performed little tweaks on it, and used modern computers to capture the dynamics in more detail. The new model proved that vibrations are indeed the cause of decreasing friction.

Rocks have the tendency to slide more when this happens because vibrational waves have effects on different rocks at different times which leads to the slide moving like a fluid. These results are consistent with Melosh's acoustic fluidization idea he proposed about 40 years ago, before computing power was enough to perform it.

With Johnson's careful analysis, the debate between rivals Melosh and Campbell, who did not believe that the acoustic fluidization mechanism could explain the findings in the simulation, has now been put to rest. The researchers hope that the results of their work can be an instrument in predicting these potentially devastating landslides.

"I would suggest that understanding why these landslides run out so far is really is a first step to understanding when and where they might occur in the future. Our work suggests that all you need is enough volume to get these long runouts," Johnson said.

The river-like flow of landslides is no longer a mystery thanks to acoustic fluidization. However, there is no reason yet to celebrate as  the findings still show that landslides can occur anywhere, says Engadget.