Forest to protect cities from earthquake
The deflected waves to protect a building can destroy the neighbor and, among the famous surface seismic waves known by seismologists as Rayleigh waves, some have wave lengths large enough not to be affected by the already envisaged seismic invisibility systems. Fortunately, these problems seem to be able to be overcome using ... trees!
Experiments carried out in France with a small pine forest not far from the campus of the Université Joseph-Fourier in Grenoble, together with numerical simulations, confirm that the trees can behave as resonators rebroadcasting the waves of Rayleigh in a certain frequency band in response to the arrival of these of an earthquake. In the end, they are sent deep into the ground, even for large wavelengths. Oddly enough, the most effective protection is obtained with trees planted in a dense and random way. It improves again by covering a larger frequency band if the trees are arranged with decreasing heights.
Yet there is a problem: at the moment, the concept only works if the waves arrive from two directions only. But the researchers are confident. They'll blow up that lock.