Wireless Sensor Networks: A bridge to the Physical World
Jeremy Elson, Deborah L. Estrin · eScholarship (California Digital Library) · 2004
Chapter 1 SENSOR NETWORKS: A BRIDGE TO THE PHYSICAL WORLD Jeremy Elson and Deborah Estrin Center for Embedded Networked Sensing University of California, Los Angeles Los Angeles, CA 90095 {jelson,destrin}@cs.ucla.edu The Quake It was in the early afternoon of an otherwise unremarkable Thursday that the Great Quake of 2053 hit Southern California. The earth began to rupture several miles under the surface of an uninhabited part of the Mohave desert. Decades of pent-up energy was violently released, sending huge shear waves speeding toward greater Los Angeles. Home to some 38 million people, the potential for epic disaster might be only seconds away. The quake was enormous, even by California standards, as its magnitude surpassed 8 on the Richter scale. Residents had long ago understood such an event was possible. This area was well known for its seismic activity, and had been heavily in- strumented by scientists for more than a century. The earliest data collection had been primitive, of course. In the 1960’s, seismometers were isolated devices, each simply recording observations to tape for months at a time. Once or twice a year, seismologists of that era would spend weeks traveling to each site, collecting the full tapes and replac- ing them with fresh blanks. If they were lucky, each tape would contain data from the entire six months since their last visit. Sometimes, they would instead discover only a few hours of data had been recorded be- fore the device had malfunctioned. But, despite the process being so impractical, the data gathered were invaluable—revealing more about the Earth’s internal structure than had ever been known before. By the turn of the century, the situation had improved considerably. Many seismometers were connected to the Internet and could deliver a continuous stream of data to scientists, nearly in real-time. Experts D R A F T Page 1 January 22, 2004, 8:01am D R A F T