Probably all of us reading this have a smartphone in our pocket. For many of us, the smartphone has become our primary method of reading and writing e-mails, messaging, and browsing the web. Though proclamations that “smartphones have replaced the personal computer” typically fall on deaf ears, the statements aren’t without merit. Indeed, smartphones have “replaced“—or more accurately, “displaced“—PC’s in several areas that they have traditionally been dominant. But how many of you look into your pocket, or on your desk, and see a scientific instrument? Well, that’s exactly what some scientists have started to do.
Though there is little fanfare outside the realm of science meetings and technical workshops, scientists around the world are now beginning to embrace the ubiquity of smartphones. And nowhere is the excitement greater than in the Earth Science community.
What is earthquake early warning?
Earthquakes take time to travel from point A to point B (the damaging waves typically travel at less than 4 km/s). Earthquake early warning takes advantage of the fact that the speed of telecommunications (i.e., the speed of light) is much faster than the speed of an earthquake. The idea is that, if you have a big population center at point B (e.g., a city), you can install a bunch of sensors around point A; as soon as the earthquake occurs, your sensors can detect and alert the people at point B before the shaking arrives.
Let’s use some real geography for a real-world example. Let’s imagine you’re sitting in your office in downtown Los Angeles, and suddenly the San Andreas fault ruptures—next Big One has just occurred, centered underneath Palm Springs, to your east (Click here for a map, for those unfamiliar with California geography). Palm Springs lies about 160 km from downtown L.A., so that means that it’s going to take somewhere in the range of 40 seconds for most of the damaging seismic waves to reach you. If you have sensors located right at the epicenter of the earthquake, in Palm Springs, those sensors will detect the earthquake immediately and relay that information to alarms in L.A. Even if it takes 10 seconds for computers to analyze the data from the sensors and send it to the alarms, you’ll still have 30 seconds of advanced warning before the bad shaking begins.
Sounds like futuristic technology? It’s not. Japan has had various kinds of earthquake early warning systems in place for decades. They started with sensors installed on their rail networks which could automatically send signals to tell trains to apply the brakes in the case of a large earthquake. That system has since evolved into a nationwide network, and alerts are sent out not only to trains, but to department stores, buildings, and factories. Since 2007, people may now receive cell phone alerts, giving them precious seconds (sometimes up to a minute) of forewarning to take cover. There are even programs for your computer, such as The Last 10-Second, that will raise an early warning and show you the progress of seismic waves in real-time.
So what, I’ll get an extra few seconds to get under a table. Big deal.
Earthquake early warning (EEW) may not seem that amazing, but it, in fact, saves a lot of money and lives. Imagine you’re riding an elevator when a catastrophic earthquake occurs. With EEW, that elevator may automatically stop at the nearest floor and let you out—before the shaking begins. Imagine the delicate work that takes place at a machining or electronics factory. If the ground suddenly starts shaking, the product—and potentially millions of dollars with it—could be ruined. But with EEW, there are a precious few seconds to safely abort the process and wait for the earthquake to subside. Imagine how thankful a surgeon in the middle of a surgery would be given an early warning before an earthquake hit. Or how about gas stoves, or even gas pipelines, that automatically shut off before the shaking begins?
Well, if you live in Japan, you don’t have to imagine, because earthquake early warning is a reality, and it’s getting better every year. But for the rest of us, it’s coming—first to the US West Coast, and then, potentially, the world.
So where do smartphones come in?
Well, seismometers—the instruments that geophysicists use to measure ground motion—are expensive. Like, really expensive; as much as a car. So it’s not really practical to place tens of thousands of seismometers all over the world in anticipation of earthquakes for which no one can accurately predict when the next reoccurrence will be. And good luck procuring a few million dollar annual budget to purchase and maintain a network of seismometers for just a small early warning system. That’s where smartphones come in—they’re cheap, they’re ubiquitous, and they nearly all have accelerometers on board.
Seismometers are basically really sensitive accelerometers. Nearly all of us have accelerometers built into our phones. What if, instead of building out a network of hundreds of seismometers in every area prone to earthquakes (and then some in areas we don’t expect—because unexpected earthquakes do happen), we could utilize the existing “seismometers” in our pockets? Well, that’s a question that scientists around the world, including those at the US Geological Survey, are increasingly talking about.
While smartphone accelerometers aren’t even close to the quality and sensitivity of a real seismometer, they just might be good enough so that, in aggregate, they can be used for real scientific utility. Many of us set our smartphones on our desks or tables while they’re not in use. During that time, they’re stationary. If they were linked into an earthquake early warning system, they could report if they experienced sudden movement. While any individual phone would not be a reliable witness to an earthquake—maybe the sudden movement was caused by it falling on the ground, or somebody picking it up, or just a glitch—if thousands of phones in an area suddenly showed movement, perhaps it is indicative of an earthquake. In this way, it may be possible for smartphones to be used in lieu of, or at least in supplement to, traditional seismic networks.
Further, this approach has important ramifications for developing countries. Once again, seismometers are expensive. But nearly everyone has a smartphone. If scientists can develop a universal and scalable system for earthquake early warning utilizing smartphones—or even small, cheap seismometers built using cell phone accelerometers for this purpose—we could build out early warning systems even for aftershocks in places like Nepal in a matter of days or weeks instead of decades. And lastly, such a system would be important for the very future of science, itself. If, as an individual, anyone could use their own smart phone to so clearly contribute to science, it would be very inspiring and empowering; we would be dramatically improving the accessibility and understanding of science for millions of people around the world.
So next time you’re sitting there thinking about how much your smartphone can do, remember that it can also be used as a scientific instrument. In the future, it just might give you an early warning for an earthquake.
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