Researchers make 'cloaking device' vs earthquakes

A group of researchers may have come up with a new way to protect vital installations from powerful earthquakes - a "wave guide" that dampens the impact.

 

The study promises to protect key structures like power plants and dams from such tremors like the magnitude-6.9 quake that hit Negros last Feb. 6.

 

"Our device is an attenuator of a seismic wave. Constructing a cylindrical shell-type waveguide that creates a stop-band for the seismic wave, we convert the wave into an evanescent wave for some frequency range without touching the building we want to protect," researchers Sang-Hoon Kim and Mukunda Das said in their abstract submitted Feb. 8.

 

A separate article on CNET said the team from the University of Manchester's School of Mathematics proposed creating barriers that would "cloak" buildings from the seismic waves of earthquakes.

 

Citing parts of the paper published last week, CNET said the researchers claim artificially engineered materials or metamaterials can potentially to safeguard critical buildings better than existing techniques.

 

"These materials would effectively convert the destructive seismic waves into a different type of wave that dissipates quickly in intensity," it said.

 

It said the team proposes creating cylinders with specially treated rubber which would be placed in the ground around a structure.

 

When the seismic waves from an earthquake cause vibrations, the waves would not "see" the building and largely pass around the structure, the team said.

 

Instead, the energy from the seismic wave would be converted into sound and heat energy, they said in the paper.

 

"Five or six years ago scientists started with light waves, and in the last few years we have started to consider other wave-types, most importantly perhaps sound and elastic waves. The real problem with the latter is that it is normally impossible to use naturally available materials as cloaks," said professor William Parnell in a statement.

 

"We showed theoretically that pre-stressing a naturally available material--rubber--leads to a cloaking effect from a specific type of elastic wave," he added.

 

The group suggested that this metamaterial barrier be used for isolated buildings or those with high social value, such as nuclear reactors and transportation infrastructure, CNET said. — TJD, GMA News