Distributed network of laptop accelerometers used as seismic detector
November 5, 2008 We're often surprised by the unforeseen applications that emerge when lateral thinking is applied to new technology - and this is certainly one of them. The Quake-Catcher Network aims to create the world’s largest earthquake monitoring system by linking internet-connected computers. The key to the system is its ability to take advantage of Sudden Motion Sensors or Active Protection Systems that are already found in many recently manufactured laptop computers. Day-to-day, these sensors are designed to protect the computer's hard disk from vibration, but by running specially designed networking software they become a far-reaching, low-cost solution for a seismic detection and early earthquake warning system.
The system works on laptops which have a built in Sudden Motion Sensors, but desktops can also be part of the network by adding inexpensive (USD$49) USB accelerometers. In fact, desktops suit the aims of the program better because they are more likely to remain in one place, so there's no guess-work involved in locating where the alert is coming from. Desktops also have the advantage of stable placement - usually on the floor or a desk as opposed to someone's lap - and because the keyboard is separate, typing does not effect the sensor. The Quake-Catcher Network keeps track of laptops using several methods. Participants can input locations into a Google Maps web interface through the site and a rough location can also be established using your IP address and the server location. The advent of GPS enabled laptops also has the potential to provide more accuracy for network. The software also caters for circumstances where laptops are not on a level surface by zeroing out each directional acceleration before it begins to monitor the sensor and the value of having a network rather than a single sensor also comes into play when establishing whether data is valid - i.e. if one laptop transmits a high-energy signal it may be an anomaly, but if numerous signals are received from one area then it's likely that an earthquake is taking place. The typing issue is overcome by the fact that the QCN only runs on laptops when the computer has been inactive for 3 minutes or more and another potential problem, the time being wrong on your computer, is addressed by software checks every 15 minutes that check your laptops time against an atomic clock at QCN to ensure data is synchronized.
The seismic data is collated and made available for analysis in several forms including a map. As well as a warning and research system, this information is designed to be used as a classroom educational tool for better understanding earthquake science.
The system is only designed to detect major shakes and is of course much less sensitive than dedicated seismic sensors which can detect small, magnitude 1.0 earthquakes and larger quakes over vast distances. It is nonetheless a cheap and effective way to harness idle CPU time and the goodwill of volunteers to help achieve the goal of warning and protecting people from harm as well as providing . The QCN has already proven its merit by detecting a magnitude 5.4 earthquake east of Los Angeles in July this year and a magnitude 5.1 event in Reno in May.