Hiding buildings from earthquakes? The cloaking technique that could make them safer
How can we protect buildings in the event of an earthquake? A European researcher has perhaps found the answer - use an invisibility cloak!
Whilst this may sound like something straight out of a science fiction novel, mathematician Dr William Parnell from Manchester University in the United Kingdom believes that their newly developed 'cloaking' device could one day protect buildings when an earthquake strikes. The technique makes an object near invisible to light, sound or vibration waves.
Cloaking devices work by covering components of structures with pressurised rubber. If applied to a building, powerful waves such as those produced by an earthquake wouldn't 'see' the building. In theory, they would pass by the structure and serious destruction would be avoided.
Outlining their findings in the journal Proceedings of the Royal Society A, the team describe how this cloaking technique could one day be important for safeguarding structures such as nuclear power plants, electric pylons and government offices - during both natural disasters and terrorist attacks.
While research into cloaking from light waves began about six years ago, there hasn't been much work carried out on waves in solid bodies such as those produced by earthquakes.
Dr William Parnell comments on the significance of these results for progress in the cloaking field: 'Significant progress has been made, both theoretically and practically in the area of cloaking. 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.'
Most recently, the concept of the invisibility cloak appeared in the Harry Potter books, with Harry donning his cloak to carry out all sorts of tasks unhindered by others noticing his moves. But will this idea transfer from the world of science fiction to the rather more serious task of risk management?
Dr William Parnell elaborates: 'We showed theoretically that pre-stressing a naturally available material - rubber - leads to a cloaking effect from a specific type of elastic wave. Our team is now working hard on more general theories and to understand how this theory can be realised in practice. This research has shown that we really do have the potential to control the direction and speed of elastic waves. This is important because we want to guide such waves in many contexts, especially in nano-applications such as in electronics, for example. If the theory can be scaled up to larger objects, then it could be used to create cloaks to protect buildings and structures, or perhaps more realistically to protect very important specific parts of those structures.'
Last spring's Fukushima earthquake in Japan refocused attention on the importance of securing nuclear power plants and ensuring they can withstand natural disasters.
Currently, a variety of projects being carried out as part of the Seventh Framework Programme of the European Atomic Energy Community (FP7 Euratom, 2007-2011) aim to further knowledge in the field of nuclear energy safety.
The new study from Dr William Parnell complements this ongoing research.
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Document Reference: Parnell, W. J., 'Nonlinear pre-stress for cloaking from antiplane elastic waves', Proc. Roy. Soc. A, 468: 563-580, 2012. doi:10.1098/rspa.2011.0477
Subject Index: Economic Aspects; Environmental Protection; Innovation, Technology Transfer; Nanotechnology and Nanosciences; Radiation Protection; Safety; Scientific Research; Security; Social Aspects