The Earth Story

The singing dunes

Lurking within the Badain Jaran desert of China amongst some of the tallest stationary dunes on the planet (up to 500 metres tall) are rare musical dunes, that boom and sing as you slide down them because of a poorly understood mechanism. The noise resulting is loud (up to 105 decibels) and deep, somewhat like a propeller plane and can last for up to a minute. One factor that certainly inhibits the property is water between the sand grains, after a rainfall for example. The structure of the dunes is crucial, as is the type of sand forming them. The noise can only be generated by creating an avalanche on the steep leeward side of the dune.

Loz

Image credit: Guo Qi

http://english.cri.cn/725/2006/06/06/[email protected]

Paper on the desert and geomorphology of the dunes, free access: http://www.casnw.net/outside/keyan/desert/人员组成/董治宝.files/已发表论文/Geomorphology%20of%20the%20megadunes%20in%20the%20Badain%20Jaran%20Desert.pdf

Physics behind the singing sand dunes revealed-Death Valley National Park

Some sand dunes produce a haunting sound when avalanches are triggered. Scientists refer to this phenomenon as “singing sand” and can also be produced by walking over the sand and by wind passing over the dunes. Interested in the mechanism behind this phenomenon, Natalie Vriend, a Ph.D student at Caltech along with professor Melany Hunt and professor Rob Clayton, probed the dunes in California’s Death Valley. The team came up with some interesting findings.

The team used geophones to measure seismic vibrations within the ground, which are similar to microphones that pick up acoustical vibrations (sound pressure) in the air. According to Vriend "The waves travelling through the dune move individual grains of sand, which exert a force on the geophone that we use for measurements”. (http://bit.ly/1Q2Lylj)

It was found that the shorter bursts of sound correspond to a surface Rayleigh wave (a type of surface acoustic wave that travel on solids) travelling radially along the surface of the dune in a nonlinear way. Vriend also points out that the long booming sounds actually originate from “linear P-waves that travel volumetrically and are reflected from internal layers inside the actual dune”. (http://bit.ly/1Q2Lylj)

-AN

Learn more about the teams findings here: http://bit.ly/1Q2Lylj

Listen to the resonating song of the dunes here: http://bit.ly/1ivQh1p

Photo: Mike Hume http://bit.ly/1M8SFas

There are sand dunes around the world that put out a strange sound when large amounts of sand avalanche down the slope. This video shows some of the results and records the sounds.

The singing dunes Lurking within the Badain Jaran desert of China amongst some of the tallest stationary dunes on the planet (up to 500 metres tall) are rare musical dunes, that boom and sing as you slide down them because of a poorly understood mechanism. The noise resulting is loud (up to 105 decibels) and deep, somewhat like a propeller plane and can last for up to a minute. One factor that certainly inhibits the property is water between the sand grains, after a rainfall for example. The structure of the dunes is crucial, as is the type of sand forming them. The noise can only be generated by creating an avalanche on the steep leeward side of the dune. Loz Image credit: Guo Qi http://english.cri.cn/725/2006/06/06/[email protected] Paper on the desert and geomorphology of the dunes, free access: http://www.casnw.net/outside/keyan/desert/人员组成/董治宝.files/已发表论文/Geomorphology%20of%20the%20megadunes%20in%20the%20Badain%20Jaran%20Desert.pdf