How Huge Subterranean Grids Could Protect Cities From Earthquakes

How Huge Subterranean Grids Could Protect Cities From Earthquakes
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French engineers have been experimenting with a technique that could redirect seismic energy away from structures such as cities, dams and nuclear power plants, sparing them from damage. It involves digging large, cylindrical boreholes into the ground, forming a defensive geometry of lace-like arrays that, researchers hope, could deflect seismic waves and thus make whole landscapes “invisible” to earthquakes.

In fact, these arrays were inspired by the same type of “cloaking” effects already used elsewhere to show “how light can be manipulated to make objects invisible,” as David Biello reports in Scientific American. These are referred to as “metamaterials”, and, thus, appropriately, the empty boreholes are described as “seismic metamaterials” in a new paper published in Physical Review Letters.

As Biello describes it, however, these boreholes would need to be “precisely tuned,” almost like musical instruments — he specifically writes that a “precisely tuned array of boreholes around a city or a nuclear power plant” would be required. This would be so that the voids could “resonate at the frequencies characteristic of quakes,” “shielding” the protected area from harm. Physics World calls this transformation seismology.

Interestingly, the deflected seismic energy wouldn’t just disappear: another city, town, or empty landscape that would not previously have been affected could now very well experience the brunt of the destruction.

There are some other implications here, then, including the potential need to designate — or even design — a kind of seismological sacrifice zone where these quakes could be directed.

Like seismic weapons, these drilled grids of empty space on the edge of the city would thus be used to send earthquakes toward other locations. Think of them as magnifying lenses in the ground for redirecting seismic destruction.

While the research is all very practical at the moment and still in its earliest stages, it’s not hard to imagine a future urban landscape — perhaps Los Angeles in the year 2094 — perforated with a new infrastructure of huge resonating voids, a kind of tectonic sitar beneath the streets that can deflect catastrophic earthquakes toward distant locations.

Perhaps led out into the desert along a long necklace of deep-earth grids, earthquakes pulse outward into a national seismic sacrifice zone in the desert, an empty expanse of land where artworks have been installed to shiver with every lurch in the soil and people come to experience the near-constant jolts and tides.

In fact, who knows: maybe you could even pair this with fracking — which is, after all, notorious for setting off earthquake swarms, as in Oklahoma — and you could effectively instrumentalize seismic activity, capturing, deflecting, and strategically reusing the effects of earthquakes on demand. [Physical Review Letters via Scientific American and The Verge]