How to prevent earthquake damage: make buildings invisible

Feb 12, 2013 by Marcia Malory report

(Phys.org)—When an earthquake strikes, damage to buildings such as nuclear power stations can worsen the catastrophe. Researchers from France's Institut Fresnel and the French division of Menard, a ground-improvement specialist company, have developed an invisibility cloak that could protect buildings during an earthquake by redirecting seismic waves around them.

The researchers studied invisibility cloaks that make objects invisible to . These cloaks are made of metamaterials smaller than the . They divert light waves around themselves, so light cannot reach anything hidden inside.

While invisibility cloaks are standard fare in science fiction and fantasy, in reality, it is very difficult to create a metamaterial capable of manipulating light waves, which are extremely short and travel very long distances. Seismic waves, however, are longer than light waves and do not travel as far, so developing a seismic metamaterial could be easier.

Last year, physicists at Mokpo National Maritime University in South Korea and the Australian National University in Canberra developed a model for a seismic . The French team, however, was the first to build and test one.

The team simulated an earthquake by using a vibraphone to create 50-hertz across a silty clay alluvial basin, up to 200 meters deep, near Grenoble, France. measured the waves' movement.

They then created a metamaterial by drilling three rows of holes into the basin. There were 10 holes in each row, spaced 1.73 meters apart. Each hole was about five meters deep and had an average diameter of 320 millimeters.

When the French team re-transmitted the 50-hertz waves, energy levels near the source of the waves almost doubled, indicating that the metamaterial was reflecting the waves, which barely made it past the second row of holes. While a seismic metamaterial like this might eventually save lives during an earthquake, engineers and physicists still need to address some important issues.

For example, it is impossible to predict the length of an earthquake's seismic waves. This makes it difficult to determine how far to space the holes in the array. A way to get around this might be to arrange the holes to match the resonance of the building needing protection.

There is also a danger that seismic waves reflected off a building could damage nearby buildings. A metamaterial that absorbs, rather than reflects, seismic might be a better choice.

Explore further: X-ray powder diffraction beamline at NSLS-II takes first beam and first data

More information: arxiv.org/abs/1301.7642

4 /5 (29 votes)

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antialias_physorg
3.6 / 5 (9) Feb 12, 2013
Good idea. I wonder if this applies to P-waves as well as S-waves.

Though the concept does not seem to apply to Earth movement that lifts/drops the affected area (as you can't move the wave out of the medium).
El_Nose
2.3 / 5 (6) Feb 12, 2013
now that my boys is the new corporate warfare...

build your new headquaters right next to the competition in an earthquake zone and If a quake hits divert all the power into the rival... want to kill a beast cut off it's head - thats what my dad taught me.

In my day son if you didn't like the competition you got rid of them.
bbarr34
3 / 5 (2) Feb 12, 2013
The waves from the earthquake would be directed towards all the building around the one with the holes drilled. Therefore, the design seems unpractical to protect more than one building at a time. A building design that could support the absorption of the seismic waves would work better. However, it needs to be determined the strength that that structure could sustain or how the initial shock could be refracted into the air. That would be a pricey measure, but would be more affective than destroying the buildings around.
baudrunner
2 / 5 (4) Feb 12, 2013
Has anybody paused to think that perhaps the structure was actually working to wrap the seismic waves around to echo off the basin wall back around the structure to the source? If it is established that this wasn't the case, then don't the results point to failure of the intent to prove the theory?
Howard_Vickridge
1.8 / 5 (5) Feb 12, 2013
We're obsessed with conquering nature. Build away from earthquake zones, simple. Cities are planning protection systems against sea-level rises. Better to use policy to make building and staying in such vulnerable areas unattractive. Grow the city up the hills and let the sea do what it will do.
El_Nose
1 / 5 (4) Feb 12, 2013
I got 1's really

look I was hoping that people would see the real way to implement this.. i person bbarr34 got close..

look i can't think of one earthquake where the epicenter was actually inside the city. put the absorbers or redirectors around city limits.

Its a HUGE project -- but you only need to do it one time and then QA test every few years for making replacements. What is spending 1 billion to LA when you could guarantee your whole city did not feel the earthquake.

kneff
1 / 5 (2) Feb 12, 2013
While I feel like tampering nature is not wise, this could actually be very beneficial. Yes, there would be a large expense right off the bat, but there is a high chance it could help to save billions in the long run. I am unsure, however, of the feasibility of being able to surround and entire city. Would there actually be enough time and resources to accommodate a whole city and if so which cities would become protected first? It is a unique idea, perhaps it just needs more planning.
PhyOrgSux
2.1 / 5 (7) Feb 12, 2013
So a "cloak" for seismic waves would cause a redirection of the waves around the cloak. Now if it then is possible to redirect the waves, perhaps they could also be redirected into some sort of a "container" (an area surrounded by these cloaks set up so as to cause these waves to bounce around until they die out).
k_m
1.7 / 5 (6) Feb 12, 2013

look i can't think of one earthquake where the epicenter was actually inside the city. put the absorbers or redirectors around city limits.

Its a HUGE project -- but you only need to do it one time and then QA test every few years for making replacements. What is spending 1 billion to LA when you could guarantee your whole city did not feel the earthquake.


Northridge earthquake epicenter was approximately at the intersection of Reseda and Sherman Boulevards.
34.207°N 118.535°W
http://www.bing.c...quake___

So which city do you protect?
k_m
1 / 5 (5) Feb 12, 2013
What if the bore holes were horizontal instead of vertical and offset similar to the steps of staircase, either ascending or descending?

Would the 'waves' be diverted up into the atmosphere or down towards the lithososphere?
Caliban
3 / 5 (2) Feb 13, 2013
It would seem that the ideal solution would be to develop a method to reflect the waves 180 degrees out of phase, and thus cancel them altogether.

Doesn't seem that this would present any more of a challenge, in principle.
wvu_student
5 / 5 (1) Feb 13, 2013
@El_Nose: A problem with placing redirectors around city limits is that cities such as LA are surrounded by suburban developments. So what would be considered "city limits?" As long as the metamaterial only reflects the waves, it would be almost impossible to surround an entire city without causing more damage to surrounding residential areas. In addition, it would be a large enough task to surround just one building, let alone an entire metropolitan area.

Regarding the article, I may have missed this but would this metamaterial protect the building from surface seismic waves in addition to body waves?
antialias_physorg
3.4 / 5 (5) Feb 13, 2013
Better to use policy to make building and staying in such vulnerable areas unattractive

The entire globe is a potential earthquake zone. If you want to make building in such zones unattractive you'd have to completely depopulate the entirety of Japan, Hawai, parts of the mediterranean, California, Turkey, ...

Then there are other factors: Most powerplants require water. Water flows in rivers. Rivers very often flow in - you guessed it - faults created by earthquakes.

Its a HUGE project -- but you only need to do it one time

Cities have a tendncy to grow. It's the problem the ancients had with city walls. After you finished building one you can go right back and start building a bigger one for all the houses that have been added since then.
A billion dollars wouldn't be enough to encompass a small neighborhood. This'd be a trillion dollar (or more) per city endeavour
Howard_Vickridge
3 / 5 (2) Feb 13, 2013
Indeed Antialias, we are but animals on the planet, and cannot protect ourselves or environments from all risks. Such is life. My suggestion of using policy to make areas unattractive for development was in relation to sea level rise. We can run to he hills! But I agree, earthquakes are a different matter. I live in New Zealand, "the shaky isles", and purposely live well away from major fault-lines. Still, I know I can't compete with the forces of mantle movement.
rubberman
2 / 5 (4) Feb 13, 2013
The geological substructure is another consideration, not all structures are built on a silty clay alluvial basin, would the method work for bedrock or shale.....
Erik
1 / 5 (1) Feb 13, 2013
What if the bore holes were horizontal instead of vertical and offset similar to the steps of staircase, either ascending or descending?

Would the 'waves' be diverted up into the atmosphere or down towards the lithososphere?


Redirecting the wave downwards might even help your neighbors by creating a shadow zone.
antialias_physorg
2.3 / 5 (3) Feb 13, 2013
Would the 'waves' be diverted up into the atmosphere or down towards the lithososphere?

No, because you have an interface (earth/atmosphere) with vastly different impedance. At such interfaces you get mostly reflection (i.e. the part of the wave energy travelling upward is mostly reflected back downward rather than being transmitted into the atmosphere.)

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