China to deploy Earthquake Early-warning systemIn May 2008, the ground beneath…

China to deploy Earthquake Early-warning system

In May 2008, the ground beneath Sichuan Province in China started to move after a fault on the edge of the Tibetan Plateau ruptured. By the time the shaking stopped, tens of thousands of people perished in one of the deadliest earthquakes of the last century.

This quake was particularly deadly because of the construction techniques used in the area struck by the quake. A combination of limited regulation and buildings built before establishment of seismic codes created buildings that stood well up against normal, everyday forces, but those same buildings crumbled when exposed to rolling ground. Had people been given even just a minute of warning to get out of these buildings, literally tens of thousands of lives could have been saved. Given this recent, catastrophic example, it seems appropriate that China announced that by 2020 they will deploy a large scale earthquake early-warning system.

It is not possible to predict earthquakes before they happen, even using an early-warning system. Rather than predicting quakes, these systems make use of the fact that light and information can travel at the speed of light and seismic waves travel through the planet at far slower speeds. If there is a seismic station close enough to an earthquake to recognize the initial shaking, that station can send out a digital warning that can trigger alarms throughout the area. This can generate a warning that arrives somewhere between seconds and even minutes before the strongest shaking of the quake arrives. These warnings can give people a chance to evacuate at-risk buildings or at least take shelter, in addition to doing other things to protect infrastructure like turning off power plants, slowing trains, and my personal favorite – opening doors on elevators and fire stations so that people and resources aren’t trapped when power is lost.

Deploying the system will require a cost of about 2 billion Yuan (about $300 million in current US dollars). It will require deploying an estimated 15,000 seismic stations in high-risk areas, with some spaced only 13 kilometers apart, and then linking those to an advanced network built to interpret the seismic signals. Presumably they will then arrange to allow access to warnings from this network, although details of that aren’t shared in the available article; everything from smartphones to appliances could in theory be linked to this network to provide available warnings. A similar system is in operation today in Japan and has successfully been used to distribute warnings before quakes to shut down trains and protect major resources.

China’s crust is loaded with buried seismic hazards. Much of the country has been assembled over the last few hundred million years out of smaller continental blocks, and it has since been heavily disrupted by the collision of India with Eurasia. It is only a matter of time before China suffers another devastating earthquake in its rural, at-risk areas, and deploying this sort of system will save lives when that next quake hits. Furthermore, as a nice benefit – this equipment will, when deployed, provide a huge amount of new information about the geology of China usable by both industry and scientists. Finally, this deployment is being coupled with a major seismic retrofitting program in rural areas, which presumably would make this system even more useful and help keep buildings standing when the next quake does hit.

It is interesting to see on their map that they are fairly rigorously following areas that have major, historic earthquakes as their main targets for deployment. Some recent work has argued this type of deployment will still have holes in it as per that view, the only reason why these areas are thought of as at high seismic risk is that they happened to have earthquakes recently when there was adequate monitoring equipment. In the long term, expansion of this system to other areas in China could be important, but for now it represents an excellent investment in protecting people and facilities.

-JBB

Image credit: China Daily
http://bit.ly/2jbkLaY

References:
http://bit.ly/2ic7rEC
https://on.doi.gov/2ixjABX
http://transweb.sjsu.edu/project/1225.html

Previous article on this type of system:
https://tmblr.co/Zyv2Js1z-rl9t
https://tmblr.co/Zyv2Js216UBbq



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